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In RST, RS = 11, RT = 9, and ST = 6. Which angle of RST has the smallest measure?

User Tim Harper
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2 Answers

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Angle R has smallest measure. Hope i helped
User Ravi Kumar Mistry
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5 votes

Answer:

Angle R

Explanation:

RST is a triangle with sides RS = 11, RT = 9 and ST = 6.

To find the measure of the angles we need to use cosines law.

The cosines law is written as c² = a² + b² -2ab(cosC) where a,b,c are sides of the triangle and C is the angle opposed to side c.

  • First we are going to find the angle RST using cosines law:

9²= 11²+6²-2(11)(6)(cosS)

81 = 121 + 36 -132cosS

81= 157 -132cosS

132cosS = 157 - 81

132cosS = 76

cosS = 76/132

cosS=.5757

S = 54.85

  • Using the same method we're going to find the angle STR

11²= 6²+9²-2(6)(9)cosT

121= 36 + 81 -108cosT

121 = 117 -108cosT

108cosT= 117-121

cosT = -4/108

cosT = .0370

T= 87.88

  • And finally solving for the angle SRT:

6²= 11² + 9² -2(11)(9)cosR

36 = 121 + 81 -198cosR

36 = 202 - 198cosR

198cosR = 202 -36

198cosR = 166

cosR = 166/198

cosR = 0.8383

R = 33.04

Therefore, we can conclude that the smallest measure is the one from angle R (∠SRT)

User Rakesh Patanga
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