Question

if sin3a=cos(a-26),where 3a is an acute angle then find the value of a.

Answer 1

given us,
3a is an acute angle
sin3a = cos(a - 26)
=> cos(90-3a)= cos(a -26)
=> 90 - 3a = a - 26
=> -3a - a = - 26-90
=> -4a = -116
=> a = -116/-4
=> a = 29
hence, a= 29
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Answer 2

Given that

 sin 3a=cos(a − 26)

⇒ cos(90 − 3a) = cos(a− 26)

⇒ (90 − 3a) = (a − 26)

⇒ 4a = 116°

a = 29°