if sina=12/13 and pi/2 < a < pi, cosB= -4/5 and pi < B < 3pi/2, find the exact value of,

a) sin(a+B)

b)cos(a+B)

c) tan(a+B)

Could someone please explain how to do this? ^^

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- Dec 5th 2010, 09:11 PMjonoeIf blahblah, Find the exact value of
if sina=12/13 and pi/2 < a < pi, cosB= -4/5 and pi < B < 3pi/2, find the exact value of,

a) sin(a+B)

b)cos(a+B)

c) tan(a+B)

Could someone please explain how to do this? ^^ - Dec 5th 2010, 09:25 PMProve It
Remember that .

You can use this fact to find the values of (remembering that it is in the second quadrant) and (remembering that it is in the third quadrant).

Using these, you can find the tangent values using .

Then use the identities

. - Dec 5th 2010, 09:29 PMjonoe
Thanks a lot.