Monday

November 24, 2014

November 24, 2014

Posted by **Kate** on Saturday, July 23, 2011 at 12:19pm.

2cos2 x - 5cos x + 2 = 0?

A) 240 degrees

B) 135 degrees

C) 270 degrees

D) 90 degrees

- Math -
**Reiny**, Saturday, July 23, 2011 at 12:42pmI will read that as

2cos^2 x - 5cos x + 2 = 0

(2cosx - 1)(cosx - 2) = 0

cosx = 1/2 or cosx = 2, the last part of course is not possible

so cosx = 1/2

x = 60° or 300°

So none of your choices work.

Both of my answers work in the original equation.

Check your typing

**Answer this Question**

**Related Questions**

Calculus - Find the exact values of the following. cos 270 degrees = 90 degrees...

Trigonometry - Solve the equation cos^2A = sin^2A + sinA when 0¨¬¡ÂA¡Â360¨¬. ...

Physics - Five Forces act on an object: 1. 60 N at 90 degrees 2. 40 N at 0 ...

physics - Five forces act on an object: 1: 60 N at 90 degrees, 2: 40 N at 0 ...

trigonometry (please double check this) - Solve the following trig equations. ...

math - For which angles beta, with 0 degrees less than/equal to beta less than/...

Precalculus - Which of the following is a solution for the equation 1/485tan^2x...

maths - write each of the following as trigonometric ratios of acute angles. (a)...

trig - How do I get exact measures? cosine 270 degrees sin 90 degrees tan 360 ...

Math - Find the approximate number of radians, to the nearest hundreth, in the ...