Suppose that
tan θ = c and 0 < θ < π/2
What is a formula for cos θ in terms of c?
i think its (sin theta / c)
2 Answers

Tan θ = c.
Using the identity,
Tan θ ^2 + 1 = sec^2 θ
Sec θ = (1 + c^2) ^1/2
Cos θ = 1/sec θ
Hence, cos θ = 1/(1 + c^2) ^1/2.

no.
sec(t)^2 – tan(t)^2 = 1
sec(t) = 1 / cos(t)
1/cos(t)^2 – c^2 = 1
1/cos(t)^2 = 1 + c^2
cos(t)^2 = 1 / (1 + c^2)
cos(t) = 1 / sqrt(1 + c^2)
There you go.