Q4 of 54 Page 312

Prove that:

Consider L.H.S

= + - 2 cos 70° cosec 20°


= + - 2 cos 70° cosec (90-70)°


= + - 2 cos 70° sec 70°


= 1 + 1 + - 2 = 0 = R.H.S.


Hence, proved.


More from this chapter

All 54 →
3

(sin 72° + cos 18°)(sin 72° - cos 18°) = 0

 3

tan 48° tan 23° tan 42° tan 67° = 1

 4

4