Question 1103241
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40 degrees and 50 degrees are complementary angles; stated differently, they can be the two acute angles of a right triangle.<br>
That means that, for you problem in particular, sin(40) = cos(50) -- according to the definition of the sine and cosine functions for a right triangle. Then
{{{sin(50)^2+sin(40)^2 = sin(50)^2+cos(50)^2 = 1}}}