SOLUTION: Please help me to solve this assignment,Given that CosA=2/5,find the exact value of Cos2A
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Question 1190008
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Please help me to solve this assignment,Given that CosA=2/5,find the exact value of Cos2A
Found 2 solutions by
Alan3354, ikleyn
:
Answer by
Alan3354(69443)
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):
You can
put this solution on YOUR website!
Look up "Double angles" on Wikipedia.
Answer by
ikleyn(52831)
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):
You can
put this solution on YOUR website!
.
Use the basic Trigonometry formula cos(2A) = 2*cos^2(A) - 1.
Substitute cos(A) = 2/5 here (as it is given), and complete the calculation on your own.
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See the compendium of basic Trigonometry formulas in the lesson
-
FORMULAS FOR TRIGONOMETRIC FUNCTIONS
in this site.
In the future, consult this lesson every time as you need some basic Trigonometry formula.