SOLUTION: complete: sin 225 cos 90 - cos 225 sin 90 =

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Question 898329: complete: sin 225 cos 90 - cos 225 sin 90 =
Found 2 solutions by stanbon, josmiceli:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
complete: sin 225 cos 90 - cos 225 sin 90
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(-sqrt(2)/2)(0) - (-sqrt(2)/2)*(1)
====
= sqrt(2)/2
===============
Cheers,
Stan H.
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Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
+sin%28+225+%29+%2A+cos%28+90+%29+-+cos%28+225+%29+%2A+sin%28+90+%29+
+cos%28+90+%29+=+0+
+sin%28+90+%29+=++1+
The problem reduces to:
+-+cos%28+225+%29+
+-cos%28+180+%2B+45+%29+
The cosine is negative in the 3rd quadrant, so
+-%28+-+sqrt%282%29+%2F+2+%29+
+sqrt%282%29+%2F+2+