Download Over Lesson 10–2

Five-Minute Check (over Lesson 10–2)
Then/Now
New Vocabulary
Key Concept: Angles of a Triangle
Example 1: Find Angle Measures
Example 2: Use Ratios to Find Angle Measures
Key Concept: Types of Angles
Example 3: Real-World Example: Classify Angles
Key Concept: Classify Triangles by Angles
Key Concept: Classify Triangles by Sides
Example 4: Classify Triangles
Over Lesson 10–2
__
Name all the sets of numbers to which 0.54
belongs?
A. rational
B. whole
C. irrational
D. rational, integer
Over Lesson 10–2
A. >
B. <
C. ≥
D. =
Over Lesson 10–2
Which list of numbers is correctly ordered from
least to greatest?
A.
B.
C.
D.
Over Lesson 10–2
Solve y2 = 12. Round to the nearest tenth if
necessary.
A. –6, 6
B. 6
C. –3.5, 3.5
D. 3.5
Over Lesson 10–2
A. 6.5 ft
B. 6.6 ft
C. 6.7 ft
D. 6.8 ft
Over Lesson 10–2
Which of the following is an example of an
irrational number?
A.
B.
C.
D.
You solved equations by adding or subtracting.
(Lesson 4–3)
• Find the missing angle measure of a
triangle.
• Classify triangles by properties and
attributes.
• line segment
• triangle
• vertex
• congruent
Find Angle Measures
Find the value of x in ΔDEF.
Write an equation.
100 + 33 + x = 180
133 + x = 180
Substitution
Simplify.
133 – 133 + x = 180 – 133 Subtract 133 from
each side.
x = 47
Answer: x is 47, so mF = 47°.
Simplify.
Find the value of x in ΔMNO.
A. 57
B. 123
C. 139
D. 303
Use Ratios to Find Angle Measures
ALGEBRA The measures of the angles of a triangle
are in the ratio 2:3:5. What are the measures of the
angles?
Use Ratios to Find Angle Measures
2x + 3x + 5x = 180
10x = 180
Write the equation.
Combine like terms.
Divide each side by 10.
x = 18
Simplify.
Since x = 18, 2x = 2(18) or 36, 3x = 3(18) or 54, and
5x = 5(18) or 90.
Answer: The measures of the angles are 36°, 54°,
and 90°.
ALGEBRA The measures of the angles of a certain
triangle are in the ratio 3:5:7. What are the measures
of the angles?
A. 12°, 60°, 84°
B. 30°, 50°, 70°
C. 36°, 60°, 84°
D. 40°, 60°, 80°
Classify Angles
HUMAN JAWS Humans have jaws that can open to
about 45°. What type of angle is formed by the jaws
of a human?
Answer: 45° is less than 90°, so it is an acute angle.
A bird’s beak can open to about 80°. What kind of
angle is this?
A. acute
B. right
C. obtuse
D. straight
Classify Triangles
A. Classify the triangle below by its angles and by
its sides.
Angles: The triangle has an obtuse angle.
Sides: The triangle has no congruent sides.
Answer: The triangle is an obtuse scalene triangle.
Classify Triangles
B. Classify the triangle by its
angles and by its sides.
Angles: The triangle has a right angle.
Sides: The triangle has two congruent sides.
Answer: The triangle is a right isosceles triangle.
A. Classify the triangle
by its angles and by its
sides.
A. right scalene
B. obtuse scalene
C. obtuse isoceles
D. acute equilateral
B. Classify the triangle by its
angles and by its sides.
A. right isoceles
B. obtuse isoceles
C. obtuse scalene
D. acute equilateral