Trigonometrical Ratios of Standard Angles [Including Evaluation of an Expression Involving Trigonometric Ratios] — MATHEMATICS STD 9 — Question
ICSE BoardEnglish MediumSTD 9MATHEMATICSTrigonometrical Ratios of Standard Angles [Including Evaluation of an Expression Involving Trigonometric Ratios]1 Mark
Question
If \sin $x = \cos y,$ then $x + y = 45^\circ$
✓
Answer
$\sin x=\cos y=\sin \left(\frac{x}{2}-y\right)$
if $x$ and $y$ are acute angles,
$x =\frac{x}{2}-y $
$x + y =\frac{x}{2} $
$\therefore x + y =45^{\circ}$ is false.
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