Posted by House on Friday, October 3, 2008 at 1:02pm.
If 0<theta<90 and tan theta= (square root 3)/2, find cos theta?
tan(t) =ã3 /2; cos(t) = 1/ã(1+(tant)^2)= 1/ã(1+3/4) = 2/ã7
right or wrong?

Math  Reiny, Friday, October 3, 2008 at 4:45pm
You are doing this the hard way.
make a diagram
since tan theta = √3/2, and tan theta = opposite/adjacent, make the oppose √3 and the adjacent 2
In your head you could do Pythagoras and get the hypotenuse √7
since cos theta = adjacent/hypotenuse
cos theta = 2/√7
which is what you got.