Expert: Sherman D. - 3/7/2004

Question
Hi, I solve this problem but I don't know how to answer the question. And I also don't know how to put it in the radian form.

Problem
Sove each equation for 0 is less than or equal to x is less than 2*pi by using trigonometric identies. Give ans to the nearest hundredth when necessary.

Sinxcosx = ½
Sinx = .5
X= .52

Cosx=.5
X= 1.05
In the book they gave the answer in the radian form:
0, pi, pi/6, 5pi/6, 7pi/6, 11pi/6
How do you know which type of radians to use and how many?

I'm also stuck on this question which is the same type of problem as before
Cos2x = 5 sin square x – cos square x
The way I answer this question is
5 sin square x – cos square x +cos2x =0
5sin square x- (cos +1)square = 0  

Answer
To know how to convert from radians to pi, so you know where the radians lay, go to www.krellinst.org/UCES/archive/resources/trig/node10.html

for math help, go to www.quickmath.com, and here are the things you should type

(sin(x))(cos(x)) = .5
go there, and you get x = -2.36 and 0.79

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Cos(x) = .5
go there and you get x = 1.05

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radians to degrees = 180/pi

0 = 0
pi = 180
pi/6 = 30
5pi/6 = 150
7pi/6 = 210
11pi/6 = 330

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(Cos(2x)) = (5(sin(x^2))) - (cos(x^2))
i went to the site and it came up with no solution.

Sorry i couldn't be of much more help, like showing you how to come up with the answers mathematically, but it has been a while since i did problems like these.