Thread: Help needed on trigonometric proofs

i was wondering if ANYONE could help me with some proofs i missed a couple days of trig. and im totally lost so here they are

1. 1-cos(2a)/sin(2a)=tana

2. cos(2a)= 1-tan^2a/1+tan^2a

3. tan(2a)= 2/cota-tana

thanks in advance

Originally Posted by bkstudent14

i was wondering if ANYONE could help me with some proofs i missed a couple days of trig. and im totally lost so here they are

1. 1-cos(2a)/sin(2a)=tana

Hi



As usual my advice is
1) learn ans know perfectly the trig identities
2) practice a lot

Originally Posted by bkstudent14

2. cos(2a)= 1-tan^2a/1+tan^2a