Quadrilaterals Worksheet Page 4
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Spanish
Sum of the Angle Measures of a Quadrilateral
The sum of the angle measures
Words
z
w
of a quadrilateral is 360°.
y
w + x + y + z = 360
Algebra
x
2 2
Finding an Angle Measure of a Quadrilateral
EXAMPLE
Find the value of x.
115
x
70 + 75 + 115 + x = 360
Write an equation.
70
260 + x = 360
Combine like terms.
75
− 260
− 260
Subtract 260 from each side.
x = 100
Simplify.
The value of x is 100.
3 3
Real-Life Application
EXAMPLE
You cut a wooden block to make a CO
2
racecar. The top right angle of the block
x
105
is 105°. What is the measure of the top
Reading
left angle?
CO
is an abbreviated
2
90 + 90 + 105 + x = 360
Write an equation.
way to refer to carbon
dioxide.
285 + x = 360
Combine like terms.
CO
− 285
− 285
Subtract 285 from each side.
2
x = 75
Simplify.
carbon
dioxide
The measure of the top left angle is 75°.
Find the value of x.
4.
5.
Exercises 10–12
120
60
x
81
x
120
124
WHAT IF?
In Example 3, the measure of the top right
6.
angle is 100°. What is the measure of the top left angle?
Section 8.2
Quadrilaterals
347
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