Question

How do you find the exact Trigonometric value of sec θ = -7/5, 180º < θ < 270º; sin θ ?

Answer 1

`Theta = 135^o` ; sin(135) = 0.7#

Explanation:

`sec (x)` is the trigonometric function defined by `1/cos(x)` or `2/(e^(ix) + e^(-ix))`
If `sec(Theta) = -7/5`, `cos(Theta) = -5/7`; `Theta = 135^o`
http://mathworld.wolfram.com/Secant.htm

For the given range of angles, just calculate the the value from the equation.

e.g. `sec(200) = 1/cos(200) = 1/-0.94 = -1.06`