Big Ideas Math Integrated I, 2016
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Big Ideas Math Integrated I, 2016 View details
5. Measuring and Constructing Angles
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Exercise 33 Page 421

When an angle is bisected, it is cut exactly in half.

m∠ RQS=63^(∘)
m∠ PQR=126^(∘)

Practice makes perfect

In this exercise we want to find m∠ RQS and m∠ PQR given that m∠ PQS=63^(∘), and that QS bisects ∠ PQR. This means that it cuts the angle exactly in half. The expression m∠ RQS indicates the measure of the angle between two rays, QR and QS. Similarly, the expression m∠ PQR indicates the measure of the angle between rays QP and QR. Let's identify these angles.


Looking at the figures and from the Angle Addition Postulate, we have that m∠ PQR is equal to the sum of m∠ PQS and m∠ RQS. We can form an equation to solve for the missing angles using the given measure and the fact that the two angles created by the bisector are equal to one another.
m∠ PQS+m∠ RQS=m∠ PQR
m∠ PQS+ m∠ PQS=m∠ PQR
63+ 63=m∠ PQR
126=m∠ PQR
m∠ PQR=126
Finally, let's summarize what we found. From the equation we got that m∠ PQR is 126^(∘). Additionally, as we previously stated, the measure of angle ∠ RQS equals the given measure of ∠ PQS. Therefore, m∠ PQS=63^(∘). m∠ RQS&=63^(∘) m∠ PQR&=126^(∘)