Download Draw Triangles

Main Idea
New Vocabulary
Key Concept: Angles of a Triangle
Example 1: Find a Missing Measure
Example 2: Real-World Example
Key Concept: Classify Triangles
Example 3:
Real-World Example
Example 4: Draw Triangles
Example 5: Draw Triangles
• Identify and classify triangles.
• triangle
• isosceles triangle
• congruent segments
• equilateral triangle
• acute triangle
• right triangle
• obtuse triangle
• scalene triangle
Find a Missing Measure
ALGEBRA Find mA.
Find a Missing Measure
The sum of the angle measures in a triangle is 180.
mA + 80° + 50° =
180°
Write the equation.
mA + 130° = 180°
– 130° = – 130°
Simplify.
Subtract 130° from
each side.
mA
=
50°
Answer: So, mA is 50°.
Find mZ.
A. 60°
B. 62°
C. 92°
D. 118°
CAPITOL BUILDING A state capitol building is
shown below. What is the missing measure in the
diagram?
To find the missing measure, write and solve an
equation.
Let x represent the missing measure.
x + 32 + 116 =
180
x + 148 = 180
– 148 = – 148
x
=
32
Write the equation.
Simplify.
Subtract 148 from each
side.
Answer: The measure of the missing angle is 32°.
BIRDHOUSES Chad made a birdhouse for his
back yard. The triangle below shows the
measures of the angles of the front of the
birdhouse. What is the measure of the missing
angle?
A. 30°
B. 60°
C. 90°
D. 100°
Classify Triangles
Classify the marked triangle below by its angles
and by its sides.
The triangle in the corner has one right angle and no
congruent sides.
Answer: So, it a right scalene triangle.
Classify the marked triangle below by its angles
and by its sides.
A. right scalene
B. right isosceles
C. right equilateral
D. right obtuse
Draw Triangles
Draw a triangle with three acute angles and three
congruent sides. Then classify the triangle.
Draw an acute angle. The two segments should be
congruent.
Draw Triangles
Connect the two segments with a line congruent to
the other two to form a triangle.
Answer:
The triangle is an acute equilateral triangle.
Draw a triangle with an obtuse angle and two
congruent sides. Then classify the triangle.
A.
C.
B.
D.
Draw Triangles
Draw a triangle with three acute angles and two
congruent sides. Then classify the triangle.
Draw an acute angle. The two segments of the angle
should be congruent.
Draw Triangles
Connect the two segments to form a triangle.
Answer:
The triangle is an acute isosceles triangle.
Draw a triangle with one obtuse angle and no
congruent sides. Then classify the triangle.
A.
C.
B.
D.