trig

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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 -

    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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