How do you simplify 4 sin 21 cos 21?

1 Answer
Alan P. ยท Johnson Z.
Nov 23, 2015

4sin(21^@)cos(21^@) = 2sin(42^@) ~~ 1.328

Explanation:

Double angle formula for sine function:
color(white)("XXX")2sin(theta)cos(theta) = sin(2theta)

4sin(21^@)(cos(21^@)) = 2(sin(2xx21^@)) = 2sin(42^@)

Using a calculator:
color(white)("XXX")2sin(42^@) = 1.328

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