Q5 of 118 Page 5

Prove that :

LHS



We know that sec (-x) = sec (x) and tan (-x) = -tan (x).




We know that when n is odd, sec → cosec and tan → cot.


= [-cosecx] [cosecx] - [-cotx] [cotx]


= -cosec2x + cot2x


= - [cosec2x – cot2x]


We know that cosec2x – cot2x = 1


= -1


= RHS


Hence proved.


More from this chapter

All 118 →
3

Prove that :

 4

Prove that :

 6

In a ∆ABC, prove that :

i. cos (A + B) + cos C = 0


ii.


iii.

7

If A, B, C, D be the angles of a cyclic quadrilateral taken in order prove that :

cs(180o – A) + cos (180o + B) + cos (180o + C) – sin (90o + D) = 0