Question

Refer to the attachments.

Please help me my question please ​

Answer 1

Answer:

Angle A= 90 degree

B & C = 45 degree

Step-by-step explanation:

Answer 2

We have,

A, B and C are interior angles of a triangle.

$\therefore \sf \: \footnotesize{A + B + C = 180 \degree}$

$\Rightarrow \sf \: \footnotesize{ B + C = 180\degree - A}$

$\Rightarrow \sf \frac{B + C}{2} = \frac{180 \degree - A}{2}$

$\Rightarrow \sf \: \frac{B + C}{2} = {\footnotesize{ 90 \degree }}- \frac{ A}{2}$

$\Rightarrow \sf \: \sin\big(\frac{B + C}{2} \big) = \sin( {\footnotesize{90 \degree}} - \frac{A}{2} )$

$\Rightarrow \sf \: \sin\big(\frac{B + C}{2} \big) = \cos( {\frac{A}{2}})$

Hence, proved!