Question

At
In a triangle ABc write cos (B+C/2)
in terms of angle A​

Answer 1

Step-by-step explanation:

We know that. .

$a + b + c = 180$

Dividing by 2 both side we get. .

$\frac{a + b + c}{2} = \frac{180}{2}$

$\frac{b + c}{2} = 90 - a$

Multiple by Cos both side

$\cos( \frac{b + c}{2} ) = \cos(90 - a)$

$\cos( \frac{b + c}{2} ) = \sin(a)$

• I hope it's help

Please Mark brainliest