Quandaries
and Queries 

Hi my name is Alex I am a fresman in college and I am in Trig. I really need help with proving this identity. I know I have to multiply the left side by either the congugate of the numerator or the congugate of the denominator, I get almost to the end but then I end up with a sign error. Please help it is driving me nuts. Thank you so much. 

Hi Alex, I don't think that the conjugate will work well here. I would multiply both sides by the denominator, 1 + cosx  sinx. Also write secx as ^{1}/_{cosx} and tanx as ^{sinx}/_{cosx}, and then multiply both sides by cosx. This will clear all the denominators. Now expand each side and simplify, rembering that 1  sin^{2}x = cos^{2}x. Cheers,Penny 

