Question

Trig ientities

Answer 1

http://www.sosmath.com/trig/Trig5/trig5/trig5.html

Answer 2

Trig identites

(1/1+tanx)+(1/1+cotx)=1
For this one, I wanted to know if 1+tanx is the same as 1+tan^2x, because 1+tan^2x=sec^2x

These are the ones that I have no idea how to do:

((cosx-cosy)/(sinx+siny))+((sinx-siny)/(cosx+cosy))=0

(sin^3x+cos^3x)/(sinx+cosx)=1-sinxcosx

csc2x=cscx/2cosx

cos3x/cosx=1-4sin^2x

**sorry I didn't type it the first time, my computer froze and posted it like that**

Answer 3

no, 1+tanx is not the same as 1+tan^2x

use your sum-to-product formulas:
cosx-cosy = -2 sin(x+y)/2 sin(x-y)/2
sinx+siny = 2 sin(x+y)/2 cos(x-y)/2
so the quotient is just -tan(x-y)/2
the 2nd term is similar

recall that (a+b)^3 = (a+b)(a^2-ab+b^2)

csc2x = 1/sin2x = 1/(2sinx cosx)

cos3x = cos(2x+x)
= cos2x cosx - sin2x sinx
and so on