Question

If sin (20 + θ) = cos 30° then find the value of θ .

Answer 1

Two angles are said to be complementary of their sum is equal to 90° .
θ & (90° - θ) are complementary angles

SOLUTION :

GIVEN:
sin (20 + θ) = cos 30°
cos (90 - (20+θ) = cos 30°

[cos (90 - θ) = sin θ]

cos (90- 20 - θ) = cos 30°
cos (70 - θ ) = cos 30°
70° - θ = 30°
70° -30° = θ
40 ° = θ

Hence, the value of θ is 40°.

HOPE THIS WILL HELP YOU..

Answer 2

Given Equation is sin(20 + theta) = cos 30

                              sin(20 + theta) = sin(90 - 30)

                              20 + theta = 90 - 30

                              20 + theta = 60

                              theta = 40.


Hope this helps!