McGraw Hill Glencoe Geometry, 2012
MH
McGraw Hill Glencoe Geometry, 2012 View details
6. The Law of Sines and Law of Cosines
Continue to next subchapter

Exercise 33 Page 594

Begin by using the Law of Cosines.



Practice makes perfect

Let's consider the given diagram. We will use the same color for a side and its opposite vertex. This will help us use the Law of Cosines and later the Law of Sines.

First, we can tell that this is not a right triangle, as the sides do not satisfy the Pythagorean Theorem.
Let's find the measures of and one at a time.

Finding

The lengths of all three sides of the triangle are given. Therefore, we can use the Law of Cosines to find
Let's substitute and to isolate
Solve for
Now, we can use the inverse cosine ratio and a calculator to find

Finding

Now that we know the measure of we can find using the Law of Sines.
Let's substitute and to isolate
Solve for
Now we can use the inverse sine ratio to find

Finding

Finally, to find we can use the Triangle Angle Sum Theorem. This tells us that the measures of the angles in a triangle add up to

Completing the Triangle

With all of the angle measures, we can complete our diagram.