Posted by **Piper** on Tuesday, February 3, 2009 at 4:27pm.

1. (P -15/17, -8/17) is found on the unit circle. Find sinΘ and cosΘ

Work:

P= (-15/17, -8/17)

cosΘ = a value

P = (a,b)

sinΘ = b value

Answer:

cosΘ = -15/17

sinΘ = -8/17

2. Should the triangle be solved beginning with Law of Sines or Law of Cosines. THen solve the triangle and found to the nearest tenth. a = 16, b = 13, c = 10.

Work:

c^2 = a^2 + b^2 -2abcosC

100-16^2+13^2-2*16*13cosC

100= 256+169 -416cosC

100=425-416cosC

-325=-416cosC

.78125=cosC

Answer: 38.6°, Law of Cosines is used

3. Should the triangle be solved beginning with Law of Sines or Law of Cosines. Then solve the triangle and round to the nearest tenth. A = 56 degrees, B = 38 degrees, a = 13.

Work:

SinA/a = SinB/b

sin56/13= sin38/b

Answer: 9.7

3. Find the exact value of tan(-3pi)

Work: tan(-3pi) = tan(-3pi+2pi) = tan (-pi) = tan (-pi+2pi) = tan (pi) = sin(pi)/cos(pi) = (0)/(-1) = 0

Answer : 0

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