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Maths True False[1 Marks ]

Triangles · Gujarat Board (GSEB) STD 9 (GSEB - English Medium). 25 questions.

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True False[1 Marks ]

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25 questions · timed · auto-graded

Question 11 Mark
Angles opposite to equal sides of a triangle are equal.
Answer
True.
Explanation:
Since the sides are equal, the corresponding opposite angles must be equal.
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Question 21 Mark
If any two sides of a right triangle are respectively equal to two sides of other right triangle then the two triangle are congruent.
Answer
False.
Explanation: The two right triangles may or may not be congrunt.
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Question 31 Mark
If the bisector of the verical angle of a triangle bisects the base, then the triangle may be isosceles.
Answer
False.
Explanation:
The angular bisector of the vertex angle is also a mediam.
⇒ The tirnagle must be a isosceles and also may be an equilateral triangle.
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Question 41 Mark
The two alitutde corresponding to two equal sides of a triangle need not be equal.
Answer
False.
Explanation: Since two sides are equal, the triangle is an isosceles triangle. The two altitudes corresponding to two equal side must be equal.
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Question 51 Mark
The measure of each angle of an equilateral triangle 60º.
Answer
True.
Explanation:
Since all the three angles of equilateral triangles are equal and sum of the three angles is 180º, each angle will be equal to $\frac{180^\circ}{3}=60^\circ.$
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Question 61 Mark
Two right triangles are congruent if hypoenuse and a side of the other trianlge.
Answer
True.
Explanation: According to RHS congruence criterion the given statment is true.
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Question 71 Mark
If the altitude from one vertex of a triangle bisects the opposite side, then the triangle may be isosceles.
Answer
False.
Explanation:
Here the altitude from the vertex is also the perpendicular bisector of the opposite side.
The triangle must be isosceles and may be an equilateral triangle.
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Question 81 Mark
All the angles of a triangle can be equal to 60°.
Answer
True.
Explanation :
According to the angle sum property of the triangle In $\triangle\text{ABC}$
$\angle\text{A}+\angle\text{B}+\angle\text{C}=180^\circ$ Now, if all the three angles of a triangle are equal to 60º Then, $\angle\text{A}+\angle\text{B}+\angle\text{C}=180^\circ$
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Question 91 Mark
Sum of the three angles of a triangle is 180°.
Answer
True.
Explanation:
According to the angle sum property of the triangle
In $\triangle\text{ABC}$
$\angle\text{A}+\angle\text{B}+\angle\text{C}=180^\circ$
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Question 101 Mark
An exterior angle of a triangle is less than either of its interior opposite angles.
Answer
False.
Explanation:
According to the exterior angle property, an exterior angle of a equal to the sum of the two opposite interior angles.
In $\triangle\text{ABC}$
Let x be the exterior angle
So,
$\text{x}=\angle\text{CAB}+\angle\text{CBA}$
Now, if x is less than either of its interior opposite angles
$\text{x}<\angle\text{CAB}+\angle\text{CBA}$
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Question 111 Mark
Difference of any two sides of a triangle is equal to the third side.
Answer
False.
Explanation:
The difference of any two sides of a triangle is less than third side.
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Question 121 Mark
Sum of any two sides of a triangle is greater than the third side.
Answer
True.
Explanation :
Given $\triangle\text{ABC},$ extend BA to D such that AD = AC.
Now in $\triangle\text{DBC},$
$\angle\text{ADC} = \angle\text{ACD } $ [Angles opposite to equal sides are equal]
Hence $\angle\text{BCD} > \angle\text{BDC}$
That is BD > BC [The side opposite to the larger (greater) angle is longer]
⇒ AB + AD > BC
$\therefore$ AB + AC > BC [Since AD = AC)
Thus sum of two sides of a triangle is always greater than third side.
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Question 131 Mark
If one angle of a triangle is obtuse, then it cannot be a right angled triangle.
Answer
True.
Explanation :
According to the angle sum property of the triangle In $\triangle\text{ABC}$ $\angle\text{A}+\angle\text{B}+\angle\text{C}=180^\circ$ Now, if a right angled triangle Then, $\angle\text{A}+\angle\text{B}+\angle\text{C}=180^\circ$ $90^\circ+\angle\text{B}+\angle\text{C}=180^\circ$ $\angle\text{B}+\angle\text{C}=90^\circ$ Also if one of the angle's is obtuse $\angle\text{B}+\angle\text{C}>90^\circ$ This is not possible. Thus, if one angle of a triangle is obtuse, then it cannot be a right angled triangle.
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Question 141 Mark
Side opposite to equal angles of a triangle may be unequal.
Answer
False.
Explanation:
Side opposite to equal angles of a triangle are equal.
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Question 151 Mark
The bisectors of two equal angles of a triangle are equal.
Answer
True.
Explanation: Since it an isosceles triangle, the lenghts of bisectors of the two equal angles are equal.
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Question 161 Mark
Sum of any two sides of a triangle is greater than twice the median drown to the third side.
Answer
True.
Explanation :
Given: In triangle ABC, AD is the median drawn from A to BC. To prove: AB + AC > AD Construction: Produce AD to E so that DE = AD, Join BE. Proof: Now in $\triangle\text{ADC}$ and $\triangle\text{EDB},$ AD = DE (by const) DC = BD(as D is mid-point) $\angle\text{ADC}=\angle\text{EDB}$ $\big($vertically opp, $\angle\text{S}\big)$ Therefore, $\triangle\text{ABE}, ​​\triangle\text{ADC}\cong\triangle\text{EDB}$ (by SAS) This gives, BE = AC. AB + BE > AE AB + AC > 2AD $\big(\therefore$ AD = DE and BE = AC$\big)$ Hence the sum of any two sides of a triangle is greater than the median drawn to the third side.
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Question 171 Mark
Of all the line segments that can be drawn from a point to a line not containing it, the perpendicular line segment is the shortest one.
Answer
True.
Explanation:
The perpendicular distance is the shortest distance from a point to a line not containing it.
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Question 181 Mark
All the angles of a triangle can be less than 60°.
Answer
False.
Explanation:
According to the angle sum property of the triangle In $\triangle\text{ABC}$ $\angle\text{A}+\angle\text{B}+\angle\text{C}=180^\circ$ Now, If all the three angles of a triangle is less than 60º Then, $\angle\text{A}+\angle\text{B}+\angle\text{C}<180^\circ$
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Question 191 Mark
A triangle can have two right angles.
Answer
False.
Explanation :
According to the angle sum property of the triangle In $\triangle\text{ABC}$ $\angle\text{A}+\angle\text{B}+\angle\text{C}=180^\circ$ Now, if there are two right angles in the triangle Let $\angle\text{B}=\angle\text{C}=90^\circ$ Then, $\angle\text{A}+90^\circ+90^\circ=180^\circ$ $\angle\text{A}+180^\circ=180^\circ$ $\angle\text{A}=180^\circ-180^\circ$ $\angle\text{A}=0^\circ$ (This is not possible.)
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Question 211 Mark
All the angles of a triangle can be greater than 60°.
Answer
False.
Explanation :
According to the angle sum property of the triangle In $\triangle\text{ABC}$ $\angle\text{A}+\angle\text{B}+\angle\text{C}=180^\circ$ Now, if all the three angles of a triangle is greater than 60º Then, $\angle\text{A}+\angle\text{B}+\angle\text{C}>180^\circ$
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Question 221 Mark
A triangle can have at most one obtuse angles.
Answer
True.
Explanation :
According to the angle sum property of the triangle In $\triangle\text{ABC}$
$\angle\text{A}+\angle\text{B}+\angle\text{C}=180^\circ$
Now, if a triangle will have more than one obtuse angle Then,
$\angle\text{A}+\angle\text{B}+\angle\text{C}>180^\circ$
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Question 231 Mark
Sum of the three sides of a triangle is less than the sum of its three altitudes.
Answer
False.
Explanation:
Sum of these sides of a triangle is greater than sum of its three altitudes.
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Question 241 Mark
If two angles of a triangle are unequal, then the greater angle has the larger side opposite to it.
Answer
True.
Explanation:
The side opposite to greater angle is longer and smaller angle is shorter in a triangle.
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Question 251 Mark
An exterior angle of a triangle is equal to the sum of the two interior opposite angles.
Answer
True.
Explanation:
According to exterior angle theorem,
$\text{ext.x}=\angle\text{CAB}+\angle\text{CBA}$
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True False[1 Marks ] - Maths STD 9 Questions - Vidyadip