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Big Ideas Math Geometry, 2014

BI

Big Ideas Math Geometry, 2014 View details

4. Equilateral and Isosceles Triangles

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Exercise 24 Page 257

Note that every side has equal length of 5 balls.

39 inches

Practice makes perfect

From the diagram, we can see that every side has equal length of 5 balls. This means that we are dealing with an equilateral triangle.

Since all the sides are congruent, we can equate their expressions. Let's choose 2x-3 and x+5. 2x-3=x+5 Now we can find the value of x.

2x-3=x+5

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Solve for x

LHS-x=RHS-x

x-3=5

LHS+3=RHS+3

x=8

Knowing that x= 8, we can calculate the exact length of the sides. To do so we will substitute the value of x to any of the expressions.

Finally, we can calculate the perimeter by adding the side lengths. 13+13+13=39 inches

Subchapter links

Communicate Your Answer p.251

Monitoring Progress p.253-255

Exercises p.256-258