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McGraw Hill Glencoe Geometry, 2012

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McGraw Hill Glencoe Geometry, 2012 View details

1. Classifying Triangles

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Exercise 49 Page 242

Equilateral triangles have congruent sides.

Value of x: 15
Side Lengths: FG=GH=HF=35

Practice makes perfect

Equilateral triangles have congruent sides. Let's indicate this on the diagram.

Congruent sides have equal length. We can use any two of the given expressions to set up and solve an equation for x. Let's use HF=x+20 and FG=3x-10.

HF=FG

HF= x+20, FG= 3x-10

x+20= 3x-10

▼

Solve for x

LHS-x=RHS-x

20=2x-10

LHS+10=RHS+10

30=2x

.LHS /2.=.RHS /2.

15=x

Rearrange equation

x=15

We can now substitute x=15 in the given expressions to get the side lengths of the triangle.

Side	Expression	x=15	Side Length
FG	3x-10	3( 15)-10	FG=35
GH	2x+5	2( 15)+5	GH=35
HF	x+20	15+20	HF=35

Subchapter links

Check Your Understanding p.240

Practice and Problem Solving p.241-243

H.O.T. Problems p.243

Standardized Test Practice p.244

Spiral Review p.244

Skills Review p.244