Memorized - University of Minnesota

2sinxcosx+ sinx= 0use sin(2x) = 2sinxcosx sinx(2cosx+ 1) = 0factor Solve sinx= 0: This gives x= 0;ˇ, since this is one of our quadrantal angles. Solve cosx= 1 2 = x y: We must have x= 1 and r= 2. Sketch: Comparing, we see the angle in the red triangle must be ˇ=3. ................
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