>>28650
how can you do 49,50 and 52 if you can't do 51? They are basically the same

I didnt do those senpai
We are only required to do numbers from every other odd

>>28656
sec(a)=1/cos(a)
csc=1/sin(a)
tan(a)=sin(a)/cos(a)
cot(a)=1/tan(a)
sin^2(a)+cos^2(a)=1
sin(a+90º)=cos(a)
(x+y)^2=x^2+2xy+y^2

use those and always replace everything with cos and sin, should be enough to solve those

I would do these, but I'm using clover on a mobile device and don't want to bother. My condolences, OP, try YouTube for tutorials. Trig is just algebra with weird new rules, it's good to force yourself to memorize the concepts (like what it means to multiply -> sets of things)

>>28650
71. is just basic algebra
assume sqrt(x^2 - 1) = x - 1 where x = sec theta
square: x^2 - 1 = (x-1)^2 = x^2 - 2x + 1
simplify: 2x = 2, x = 1

The equation is only correct if sec theta = 1/cos theta = 1, that is, if theta = 2 pi n (integer n) and is not an identity.

>>28650
51)
use the binomial formula (a+b)(a-b) = a^2 - b^2 replace tan x and sec x by sin x and cos x
use sin^2 x +cos^2 x = 1

55) s^2 - 4 = (s - 2)(s + 2)

59) simply replace sec and tan

63) sin^2 x + cos^2 x = 1

67) use the addition theorems if you have them: sin(2x) = 2sin(x)cos(x) and you see that the equation is only valid if sin x = 0 (or if cos x = 1).