Law of Cosines

Question 1

Bethany used the steps below in an attempt to solve for angle B in triangle ABC. Where is Bethany’s error?

Revolt · Accepted Answer

Bethany took the square root of each squared term before isolating cosB and solving for B.

Question 2

Which equation can be used to solve for x in the triangle below?

Revolt · Accepted Answer

x squared equal to 4 point 7 squared plus 4 point 0 squared - 2 (4.7) (4.0) cosine 41 degree.

Question 3

In triangle RST, RS = 6 cm, ST = 7 cm, and RT = 8 cm. What is the approximate measure of the largest angle in the triangle?

Revolt · Accepted Answer

75.5°

Question 4

What is the approximate measure of angle T in the triangle below?

Revolt · Accepted Answer

79°

Question 5

What is the approximate length of the missing side in the triangle below?

Revolt · Accepted Answer

21.3 mi.

Question 6

Four students drew four different triangles in math class. Which triangle can be solved using only the law of cosines?

Revolt · Accepted Answer

Saki’s triangle

Question 7

A 15-foot flagpole leans slightly, such that it makes an 80° angle with the ground. The shadow of the flagpole is 10 feet long when the sun has an unknown angle of elevation. How could the angle of elevation of the sun, x, be determined?

Revolt · Accepted Answer

by determining the length of TV using , and then determining the value of x using

Question 8

An archer fires two arrows into a raised target, as represented in the diagram below. About how much greater of an angle did the archer need to use in order for the second arrow to land 7 feet higher than the first arrow?

Revolt · Accepted Answer

8.7°

Question 9

A ship heads due north for x miles, then turns 25° east of north and travels for another y miles. Which expression represents the distance the ship is from the original starting point?

Revolt · Accepted Answer

StartRoot x squared plus y squared minus 2 xy cosine 155 degree EndRoot.

Question 10

What is the approximate length of the third side of the triangle below?

Revolt · Accepted Answer

35.5 mm

Law of Cosines Answers

More from this Course

TRY EDGENUITY HACKS