# Solving a Trig equation by graph

• Nov 29th 2006, 07:10 AM
kcsteven
Solving a Trig equation by graph
I need to use the graphing calculator to approximate, to three decimal places,for the solutions to the homework problems I am working on, giving all the solutions possible.
Here are two of the even ones in the book.
cos(x)=2x^2
x=?

cos(x)=x^2/2
x=?

I would appreciate an example of any method to use so I can grasp this and finish my homework, so I can study for another class. This website is such a help, we are very fortunate to have a site like this to help us better understand the concepts we are being taught.
Thank you very much!!
Keith Stevens
• Nov 29th 2006, 07:38 AM
Soroban
Hello, Keith!

Quote:

Use a graphing calculator to approximate the solutions to three decimal places.

$\cos x \:=\:2x^2$

Try graphing $y = \cos x$ and $y = 2x^2$

. . and locate their intersections.

• Nov 29th 2006, 07:49 AM
earboth
Quote:

Originally Posted by kcsteven
I need to use the graphing calculator to approximate...

Hello,

which calculator do you use?

Quote:

Originally Posted by kcsteven
...
Here are two of the even ones in the book.
cos(x)=2x^2
x=?

...

1. Draw the graphs of
$y=2x^2\text{ and }y=\cos(x)$