Pearson Geometry Common Core, 2011
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Pearson Geometry Common Core, 2011 View details
6. Dilations
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Exercise 63 Page 593

You will need the Polygon Angle Sum Theorem.

40

Practice makes perfect

We want to find the value of c, which is the measure of the angle ∠ Z. We are given that TRSU ~ NMYZ.

Since the polygons are similar, we know that the corresponding angles are congruent. ∠ T ≅ ∠ N As we can see, ∠ N is congruent to ∠ T. Therefore, their measures are equal. m ∠ N= m ∠ T = 120 We know the measures of ∠ N, ∠ M, and ∠ Y. To find the measure of ∠ Z, we can use the Polygon Angle Sum Theorem. m∠ N +m∠ M+m∠ Y+m∠ Z = (n-2)180 Since our polygons are quadrilaterals, n=4. Let's substitute this value and the measures of the given angles into the above equation and solve for m∠ Z.
m ∠ N + m ∠ M + m ∠ Y + m ∠ Z = (n-2)180
m ∠ N + m ∠ M + m ∠ Y + m ∠ Z = ( 4-2)180
120 + 50 + 150+ m ∠ Z =( 4-2) 180
Solve for m ∠ Z
320 + m ∠ Z= 2*180
320+ m ∠ Z=360
m ∠ Z= 40
Therefore, c=40.