SOLUTION: Use a cofunction identity to write an equivalent expression. cos(20°)

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Question 1105164: Use a cofunction identity to write an equivalent expression.
cos(20°)

Answer by ikleyn(52813) About Me  (Show Source):
You can put this solution on YOUR website!
.
cos(a) = sin(90°-a)  ====>


cos(20°) = sin(90°-20°) = sin(70°).