Second, sin 30° is NOT 0.643. It is 0.5. A quick check on the calculator shows that you probably meant sin 40° ≈ 0.643.
And third, you already posted this problem before (http://www.mathhelpforum.com/math-he...em-153105.html), but you neglected to give use sin 40° and sin 25°. Please make sure to copy the ENTIRE problem accurately, because it is frustrating to try to work on a problem with incomplete or incorrect information.