Question

If sin 3A = cos (A - 36'), where 3A is an acute angle, find the value of A.​

Answer 1

Correct Question

If sin 3A = cos (A -36° ), where 3A is an acute angle, find the value of A.

Answer:

Given:

Sin3A = cos (A - 36°) .(1)

Proof:

A = ?

Solution:

Sin3A = Cos (90°-3A)

Put this value of Sin3A in (1)

=> Cos (90°-3A) = cos( A - 36°)

90° - 3A and A - 36° Both are Acute Angles ,

Therefore,

=> 90° - 3A = A - 36°

=> -3A -A = -36° - 90°

=> -4A = -126°

=> A = -126° /-4

=> A= 63/2

=> A= 31.5°

Answer 2

Step-by-step explanation:

Cos(90-3A)=cos(A-36)

90-3A=A-36

126=4A

A=126/4=63/2