# Evaluate 2sin^2 225 - tan 135

2
by marjonaleta

2014-05-28T16:47:37+08:00

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2sin^2 225 - tan135
2(-sqrt(2)/2) - (-sqrt(2)/2)
-2sqrt(2)/2 + sqrt(2)/2

=-sqrt(2) /2

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2014-05-28T16:54:46+08:00

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The reference angle of 225º is 45º. Since it is in QIII, sin 225º = -.

The reference angle of 135º is also 45º. Since it is in QII, tan 135º = -1

Substituting those values, we have

2 (- )² - (-1)

= 2 (2/4) + 1 = 2