Michael J. answered 03/16/15
Tutor
5
(5)
Understanding all Sines of Triangles
sin20 - (1/(cos20)) + cos20
Now we have an expression in terms of sine and cosine. Let's rewrite the expression so that we have no denominators when we simply.
(cos20 sin20 - 1 + cos40) / cos20 =
(cos20 (1 - cos20) - 1 + cos40) / cos2 =
(cos20 - cos40 - 1 + cos40) / cos2 =
(cos20 - 1) / sin20 =
(cos0 + 1)(cos0 - 1)(cos-20)