Question

if sin2a = cos (a-18) the find the value of a

Answer 1

Answer:

Step-by-step explanation:

Sin2a=cos(a-18)

[SinA=cos (90-A)]

Cos(90-2a)=cos (a-18)

90-2a=a-18

90+18=a+2a

108=3a

a=108/3

a=36°

Answer 2

Answer: The value of a is 36°.

Step-by-step explanation:

Since we have given that

$\sin 2a=\cos (a-18)$

We need to find the value of 'a'.

As we know the relation between "Sine and Cosine":

$\sin(90-a)=\cos a$

so, our equation becomes,

$\sin2a=\cos(a-18)\\\\\cos(90-2a)=\cos(a-18)\\\\90-2a=a-18\\\\90+18=a+2a\\\\108=3a\\\\a=\frac{108}{3}\\\\a=36^\circ$

Hence, the value of a is 36°.