- #1
tornzaer
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Homework Statement
1. (sinx - cosx)(sinx + cosx) = 2sin^2x-1
2. (2sinx + 3cos)^2 + (3sinx - 2cosx)^2 = 13
Homework Equations
N/A
The Attempt at a Solution
For 1. L.S. = sinx^2+sinxcosx-sinxcosx-cosx^2, the sinxcosx cancels and I'm lost.
I haven't a clue how to do the second one.
I missed a couple of day of school because of the flu before christmas break, so I need to understand this. Some please help.