try using the identity
sec^2 x = 1 + tan^2 x
It should get you through most of these
5. Prove: Tan beta sin beta + cos beta = sec beta
6. Prove: ( tan y cos^2 y + sin^2 y)/ (sin y) = cos y+sin y
7. Prove (1+tan theta)/(1-tan theta) = (sec^2+2tan theta) /(1-tan^2 theta)
1 answer