Expert: Sherman D. - 5/3/2005

Question
1) use the half-angle formula to find sin75 degrees w/o a calc.
2) use half-angle formula to find tan75 degrees w/o a calc.

Answer
By the way, these are in degrees, if you want them in radians, go to www.quickmath.com

sin((1/2)A) = sqrt((1/2)(1 - cos(A)))
sin((1/2)75) = sqrt((1/2)(1 - cos(75)))
sin(37.5) = sqrt((1/2)(1 - .258819045)
.608761429 = sqrt((1/2)(.741180954))
.608761429 = sqrt(.370590477)
.608761429 = .608761429

So the answer is .6088

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tan(75/2) = .767326988
tan(37.5) = .7673

It would be difficult for a person to do it without a calculator.