# pre calc

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suppose beta is an angle in the second quadrant and tan beta=-2. Fine the exact vaule of sin beta and cos beta

• pre calc -

draw a right-angled triangle in the second quad
so that tan B = -3/1, that is make the opposite 3 and the adjacent -1, thus the hypotenuse is √10
so y=3, x = -1, r=√10

sinB = 3/√10, cosB = -1/√10

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