Posted by **jj reddick** on Friday, October 22, 2010 at 8:48pm.

Suppose that sin x = 1/5 and cos y = 2/3, and x and y are each angles in Quadrant 1. Determine sin(x+y).

- trig -
**Reiny**, Friday, October 22, 2010 at 10:53pm
make triangles for each case , then use Pythagoras

if sinx = 1/5, then cosx = √24/5

if cosy = 2/3 , the siny = √5/3

sin(x+y) = sinxcosy + cosxsiny

= (1/5)(2/3) + (√24/5)(√5/3)

= (2 + √120)/15

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