McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
4. Parallel Lines and Proportional Parts
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Exercise 66 Page 581

Since S is the incenter of triangle PLJ, SJ is the bisector of ∠ J.

37.5^(∘)

Practice makes perfect

Let's begin with recalling the Incenter Theorem. The angle bisectors of a triangle intersect at a point called the incenter that is equidistant from the sides of the triangle. Since we are given that S is the incenter of triangle PLJ, PS, LS and JS are the bisectors of ∠ P, ∠ L and ∠ J respectively.

Since we are given that m∠ MPS is 28^(∘) and m∠ SLK is 24.5^(∘), we can evaluate m∠ P and m∠ L by multiplying the given angle measures by 2. m∠ P=2* 28^(∘)=56^(∘) m∠ L=2* 24.5^(∘)=49^(∘) Now, using the fact that the sum of the measures of each triangle is 180^(∘), we will evaluate m∠ J.
m∠ P+m∠ L +m∠ J=180^(∘)
56^(∘)+ 49^(∘)+m∠ J=180^(∘)
105^(∘)+m∠ J=180^(∘)
m∠ J=75^(∘)
The measure of ∠ J is 75^(∘). Since SJ divides this angle into two congruent angles, the measure of ∠ SJP will be one half of the measure of 75^(∘). m∠ SJP=1/2*75^(∘)=37.5^(∘) The measure of ∠ SJP is 37.5^(∘).