SOLUTION: please help me with this problem. Without using a calculator, determine the exact value of sin 20 sec 70.

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Question 1019984: please help me with this problem.
Without using a calculator, determine the exact value of sin 20 sec 70.
Answer by richard1234(7193) About Me  (Show Source):
You can put this solution on YOUR website!
Hint: sec 70 = 1/(cos 70). Use the fact that sin x = cos (90-x).