Question

if cos (40 + X) = sin 30 find the value of x
plz help​

Answer 1

cos(40+x) = sin 30°..... eq.1

sin 30° = 1/2......eq.2

Therefore, from eq.1 &eq.2:

cos(40+x) = 1/2.......eq.3

cos 60°= 1/2........eq.4

Therefore, from eq.3 & eq.4:

cos(40+x) = cos 60°

x = 60-40

x = 20°

Answer 2

$given \: \cos(40 + x) = \sin(30)$
$\cos(40 + x) = \cos(90 - 30) \\ 40 + x = 90 - 30 \\ 40 + x = 60 \\ x = 20$