Question

if sin ( x + 20°) = cos x, then the value of x is

Answer 1

sin = cos at 45o angle
x + 20 = 45,
x = 25.

Answer 2

well this is how the question is done

cos(x) = sin(90 - x) this it the complementary angles and trig ratios property

here is an example



but anyway you can now say

\[\sin(x + 20) = \sin(90 - x)\]

since the ratios are the same you can equate the angles

x + 20 = 70 - x

just solve for x...

hope this helps...

p.s. the answer isn't 25 degrees