Download Math Skills Study Guide

N am e
D ate
Period
Math Skills Study Guide
Triangles
A trian gle is a figu re w ith th ree sides and th ree angles. T he su m of the m easu res of the angles
of a triangle is 180°. You can use th is to find a m issing angle m easu re in a triangle.
1
E X A MP L E
Fin d the value of x in
#
ABC.
¡
x + 66 + 52
x + 118
- 118
x
=
=
=
180
180
118
62
The sum of the measures is 180.
S imp lify .
S ub trac t 118 from eac h sid e.
Y¡
¡
"
$
T he m issing angle is 62°.
Triangles can be classified by the m easu res of their angles. A n acute triangle has th ree acute
angles. A n obtu se trian gle has one obtuse angle. A right trian gle has one right angle.
Triangles can also be classified by the lengths of their sides. Sides that are the sam e length are
con gru ent segm ents and are often m arked by tick m arks. In a scalene trian gle, all sides have
different lengths. A n isosceles triangle has at least tw o congruent sides. A n equ ilateral
trian gle has all th ree sides congruent.
2
E X A MP L E
C lassify the trian gle by its an gles an d by its sides.
T he triangle has one obtuse angle and tw o sides the
sam e length. So, it is an obtuse, isosceles triangle.
¡
E X E R C ISE S
Fin d the m issin g m easu re in each trian gle. T hen classify the trian gle as acute, right, or obtu se.
1.
2.
¡
3.
¡
Y¡
Y¡
¡
¡
Y¡
¡
C lassify each trian gle by its an gles an d by its sides.
5.
4.
6.
¡
¡
¡
¡
¡
¡
©Glencoe/McGraw-Hill
53
Core-Plus Mathematics, Course 1
N am e
D ate
Period
Math Skills Study Guide
Triangles
Fin d the m issin g m easu re in each trian gle. T hen classify the trian gle as acute, right,
or obtuse.
1.
¡
¡
Y¡
2.
3.
¡
Y¡
Y¡
¡
¡
4.
Y¡
¡
5.
6.
Y¡
¡
¡
¡
¡
Y¡
7.
8.
9.
Y¡
¡
Y¡
¡
¡
¡
¡
Y¡
C lassify each trian gle by its an gles an d by its sides.
10.
11.
12.
¡
¡
¡
13.
¡
¡
¡
14.
15.
¡
¡
¡
¡
16.
17.
18.
¡
¡
¡
¡
¡
©Glencoe/McGraw-Hill
54
Core-Plus Mathematics, Course 1