McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
4. Proving Angle Relationships
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Exercise 1 Page 304

What is the measure of a right angle? Are ∠ 2 and ∠ 3 complementary?

Measures: m∠ 1=90, m∠ 2=26, and m∠ 3=64
Theorems: Supplement Theorem and Complement Theorem

Practice makes perfect

Since ∠ 1 is a right angle, we know m∠ 1=90. Now, let's add some labels to the given diagram.

We can see that ∠ 1 and ∠ ABD form a linear pair. Therefore, the Supplement Theorem gives us the following relation. m∠ 1 + m∠ ABD = 180 We can find m∠ ABD by substituting m∠ 1= 90 into this equation.
m∠ 1 + m∠ ABD = 180
90 + m∠ ABD = 180
m∠ ABD = 90
Now, since ∠ 2 and ∠ 3 are adjacent angles that form the right angle ∠ ABD, by using the Complement Theorem, we can say that ∠ 2 and ∠ 3 are complementary angles. m∠ 2 + m∠ 3 = 90 To find the measure of m∠ 3, we substitute m∠ 2= 26 into the equation above and solve it.
m∠ 2 + m∠ 3 = 90
26 + m∠ 3 =90
m∠ 3 = 64
Finally, we found the measure of each numbered angle. & m∠ 1=90 & m∠ 2=26 & m∠ 3=64