# Trignometry questions EASY HELP

1. Which is a solution to the equation below? sin2xsecx=1

2. What is the exact value of cos15 degrees?

3. Which expression is equivalent to the expression below? cos^2 xsin^2?

4. What is the exact value of cos2theta? one side is 8 and the other is 15

5. The angle x lies in quadrant ll. If sinx=3/5, then what is the exact value of tan2x?

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2. 👎 0
3. 👁 261

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2. This assignment is obviously meant to study the double angle formulas

1.
sin 2x secx = 1
2sinxcosx(1/cosx) = 1
sinx = 1/2
so x is in I or II
x = 30 or 150 degrees or pi/6, 5pi/6 radians

2. use cos2A = 1 - 2cos^2 A
cos 30 = 1 - 2cos^2 A
you should know cos 30, sub it in and simplify

how about you trying some of these.

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3. in #2 I had my formula backwards

should say

cos 2A = 2cos^2 A - 1
cos 30 = 2cos^2 15 - 1

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