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Erin K.

asked • 10/18/12


Simplify by using the double angle formula.

3 Answers By Expert Tutors


Robert J. answered • 10/19/12

4.6 (13)

Certified High School AP Calculus and Physics Teacher

Rini C.

Hi Robert,

The question was to simplify 2 sin18cos18  Wouldn't the simplest answer be sin36= sin (2x18)?

Why would I try to use the algorithm above?




Robert J.

Thanks for your response.

As a high school teacher who answered about 25,000 math problems in the internet, I can't believe that 2 sin 18 cos 18 = sin 36 is all you need to solve. Since 18 degree is a special angle, most likely you are asked to evaluate it. This problem can be found in many precalculus textbooks, such as in the "Avanced Mathematics" by Mr. Brown.



Arturo O.

sin(2x) = 2 sin(x) cos(x) is an identity, which is true for all x.


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