MCQ
$\sin ^2 65^{\circ}+\sin ^2 25^{\circ}=$ ?
  • A
    $0$
  • $1$
  • C
    $\frac{3}{4}$
  • D
    None of these

Answer

Correct option: B.
$1$
$\sin ^2 65^{\circ}+\sin ^2 25^{\circ} .$
$=\left[\sin \left(90^{\circ}-25^{\circ}\right)\right]^2+\sin ^2 25^{\circ} .$
$=\left(\cos 25^{\circ}\right)^2+\sin ^2 25^{\circ} .$
$=\cos ^2 25^{\circ}+\sin ^2 25^{\circ}$
$=1$

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