Question

1.)Cos9x-cos5x/sin 17x -sin3x=-sin2x/cos 10x


2.)sin(A+B)/sin(A-B) = tan A + tan B/tan A-tan B

3.) cot A-1/2- sec^2 = cot A/ 1+tan A

Answer 1

See the attachments I hope it will help you^_^

THANKS ❤:)

#Nishu HarYanvi ♥

Answer 2

2).

$from \: r.h.s. \: \: \ \frac{ \tan(a) + \tan(b) }{ \tan(a) - \tan(b) } \\ \\ = \frac{ \frac{ \sin(a) }{ \cos(a) } + \frac{ \sin(b) }{ \cos(b) } }{ \frac{ \sin(a) }{ \cos(a) } - \frac{ \sin(b) }{ \cos(b) } } \\ \\ = \frac{ \sin(a) \cos(b) + \cos(a) \sin(b) }{ \sin(a) \cos(b) - \cos(a) \sin(b) } \\ \\ = \frac{ \sin(a + b) }{ \sin(a - b) } = \: \: l.h.s \: \: proved$