Question 397291
"Express sinA in simplest form." Triangle side lengths: a=4, B=b, 
C(hypotenuse)=4 sqrt ( 5 ). 
Ive never even known what sin does, ive seen it on calculators but thats its.
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Draw a right triangle.
Label the right angle "C".
Label the hypotenuse "c"
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Label the side opposite angle B, b
Label the side opposite angle A, a=4.
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By definition, sin(A) = (side opposite A)/(hypotenuse) = 4/c
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You may find other information about right triangle trigometry
by using Google to search the web.
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Cheers,
Stan H.