Question

a
12. सिद्ध कीजिए कि -
| cos 40° + cos 50°
sin 40° + sin 50°​

Answer 1

Q: Prove that

cos 40° + cos 50°= sin 40° + sin 50°

Solution :

L.H.S : cos 40° + cos 50°

We know,

cos (90 - Φ) = sin Φ

= cos (90 - 50°) + cos (90 - 40°)

= sin 50° + sin 40°

Here,

sin 50° + sin 40° = sin 40° + sin 50°

Hence,

L.H.S = R.H.S Proved

Answer 2

Answer

To prove:

cos 40° + cos 50° = sin 40° + sin 50°

Proof:

L.H.S.

cos 40° + cos 50° = sin (90 - 40) + sin (90 - 50) [°.° cos Ø = sin (90 - Ø)]

=> sin 50° + sin 40°

L.H.S. = R.H.S.

HENCE PROVED