Question

If cos x = cos 40 sin 50 + sin 40 cos 50, then find the value of x.

Answer 1

Same question answered by me before.

I will write that only

Step-by-step explanation:

Given :

• cos x = cos 40° sin 50° + sin 40° cos 50°

Find :

• The value of x.

Solution :

sin 50° = sin (90° - 40°) = cos 40°

cos 50° = cos (90°- 40°) = sin 40°.

So,

➡ cos x = cos40° cos40° + sin 40° sin 40°

➡ cos x = cos² 40° + sin² 40° = 1

➡ cos x = cos 0°

➡ x = 0°.

Hence :

The value of x is 0°.

Answer 2

◾cos x=cos40 sin50+sin40 cos50

=cos(90-40) sin50+sin(90-40) cos50

=sin50 sin50+cos50 cos50

=sin250+cos250              (sin2A+cos2A=1) 

=1

cos 0 = 1

therefor x=0