Trigonometry
posted by Alonso .
1.Solve tan^2x + tan x – 1 = 0 for the principal value(s) to two
decimal places.
6.Prove that tan y cos^2 y + sin^2y/sin y = cos y + sin y
10.Prove that 1+tanθ/1tanθ = sec^2θ+2tanθ/1tan^2θ
17.Prove that sin^2wcos^2w/tan w sin w + cos w tan w = cos wcot w cos w
23.Find a counterexample to shows that the equation sec a – cos a = sin a sec a is not an identity.

1.
Some students like to look at these types the following way:
let tanx = y, to get
y^2 + y  1 = 0
by formula ...
y = (1 ± √5)/2
so tanx = (1 ± √5)/2
using your calculator ....
x = 31.72° or 211.72°
or tanx = (1  √5)/2
x = 121.72° or 301.72°
#6, 10, 17,
establish correct order of operation, by using brackets.
#23
just pick any angle you want and use your calculator
or pick a = 30°, (you should know the trig values for 30°)