How would I solve the equation 4sinxcosx=1?

I've completed every math problem on my assignment except this one. My teacher gave us answers to the problem, but I really don't know how the answers are what they are. I have no idea why, but I just can't get it.

Directions: Solve each given 0 is less than or equal to x less than 360.

The answer's supposed to be 15 degrees, 75 degrees, 195 degrees, and 255 degrees.

Could anyone show me how to at least work the problem?

I've gotten 4sinxcosx-1=0, but I can't get any further than that.

Thank you SO MUCH!

1 Answer

  • Recall that sin(2x) = 2sinx cos(x).

    So your equation can be written as


    sin(2x) = 1/2.

    2x = 30 + K*180


    x= 15 + k*90

    In order x to be between 0 and 360, we choose k=0,1,2,3

    So x=15, 105, 195 and 225 degrees.

Leave a Reply

Your email address will not be published. Required fields are marked *

Related Posts