Question

Find the value of \(\theta\), \(0^\circ \le \theta \le 90^\circ\), such that \(\cos 5^\circ = \sin 25^\circ + \sin \theta\). (Give your answer in degrees, not radians.)

Answer 1

Help much appreciated!

Answer 2

Hint :

sin(25) = sin(90-65) = cos(65)

Answer 3

Next, to isolate \(\theta\), use below identity
CosC - CosD = 2Sin[(C+D)/2]Sin[(D-C)/2]