Posted by **Sharon** on Sunday, April 20, 2008 at 11:03pm.

Find the solutions for sec^2x+secx=2 that fit into the interval [0, 2pi]

I figured out that pi/3 (after factoring and switching things around) was a solution, but then I got stuck on cos x = 1/3.

- Pre-Calculus -
**Reiny**, Monday, April 21, 2008 at 12:31am
no!

why don't you factor it with the secant as is

sec^2 x + secx - 2 = 0

(secx + 2)(secx-1) = 0

secx = -2 or secx = 1

cosx = -1/2 or cosx = 1

from cosx = -1/2, x = 120º (2pi/3) or 240º (4pi/3)

or

from cosx = 1, x = 0 or 360º (0 or 2pi)

## Answer This Question

## Related Questions

- Pre-Calculus - cos^2(x) + sin(x) = 1 - Find all solutions in the interval [0, ...
- Pre-Calc/Math - Use factoring, the quadratic formula, or identities to solve cos...
- solving trig. equations - tan(3x) + 1 = sec(3x) Thanks, pretend 3x equals x so ...
- Pre-Calculus - Can someone please explain on how to solve this equation so I can...
- Pre-calculus - Prove the following identities. 1. 1+cosx/1-cosx = secx + 1/secx...
- math - find all solution to the equation 3 cos(x+4)=1. in the interval of 0<x...
- Math - Can I please get some help on these questions: 1. How many solutions does...
- Trig verifying identities - I am having trouble with this problem. sec^2(pi/2-x...
- pre cal - Find all solutions in the interval[0,2pi),cos x/2-sinx=0
- pre-calculus - solve cos 2x=secx for 0(<=)x<2pi using trigonometric ...

More Related Questions