SOLUTION: Use the sum and difference identity to write the expression as the ine, cosine or tangent of an angle.
cos20degreescos30degrees-cos20degreessin30degrees
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-> SOLUTION: Use the sum and difference identity to write the expression as the ine, cosine or tangent of an angle.
cos20degreescos30degrees-cos20degreessin30degrees
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Question 773336: Use the sum and difference identity to write the expression as the ine, cosine or tangent of an angle.
cos20degreescos30degrees-cos20degreessin30degrees Answer by Edwin McCravy(20060) (Show Source):
cos(A+B) ≡ cos(A)cos(B) - sin(A)sin(B)
Let A = 20° and B = 30°
cos(20°+30°) ≡ cos(20°)cos(30°) - sin(30°)sin(20°)
Answer: cos(50°)
[Incidentally you can type the little circle degree mark °
by holding down the ALT key while you type 248 on the keypad
at the far right of your keyboard. When you let up the ALT
key the ° will appear on your screen.]
Edwin
