posted by gin on .
For each expression in column I, choose the expression from column II to complete an identity:
Column I Column II
1. -tanxcosx A. sin^2x/cos^2x
2. sec^2x-1 B. 1/sec^2x
3. sec x/cscx C. sin(-x)
4. 1+sin^2x D.csc^2x-cot^2x+sin^2x
5. cos^2 x E. tanx
I figured #1 is C, #2 is A, And #4 is D, but I am not sure about the rest. Please give answers and explain. Also, for the following, verify that each trig equation is an identity and explain why. NOTE: I using @ to mean angle.
6. cot^2t-1/1+cot^2t = 1-2sin^2t
7. 1-cos@/1+cos@ = 2csc^2@-2csc@cot@-1