Big Ideas Math Geometry, 2014
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Big Ideas Math Geometry, 2014 View details
5. Measuring and Constructing Angles
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Exercise 29 Page 44

The sum of the unknown angles is equal to m∠ RST.

m∠ RSQ=32^(∘)
m∠ TSQ=58^(∘)

Practice makes perfect

The expression m∠ RSQ indicates the measure of the angle between two rays, SR and SQ. Similarly, the expression m∠ TSQ indicates the measure of the angle between rays ST and SQ. To find their measures, let's start by identifying the three angles on a diagram.

Looking at the figures, and by the Angle Addition Postulate, we can see that m∠ RST is equal to the sum of m∠ RSQ and m∠ TSQ. We can solve for x by creating an equation using the expressions for the two smaller angles and the value of the larger angle. Note that ∠ RST is a right angle which is always equal to 90^(∘).
m∠ RSQ+m∠ TSQ = m∠ RST
(15x-43)+(8x+18)=90
15x-43+8x+18=90
23x-25=90
23x=115
x=5
Having solved the equation, we can calculate the individual angles by substituting x= 5 into the expressions for the unknown angles. m∠ RSQ:& 15( 5)-43=32^(∘) m∠ TSQ:& 8 ( 5)+18 =58^(∘)