Download Angle Measure

• Ray-- A part of a line that extends indefinitely
in one direction from a fixed point.
• Opposite rays-- Two rays that are part of the
same line and have only their endpoints in
common. In the figure,
and
are
𝑌𝑋
𝑌𝑍
opposite rays.
• Angle-- A figure formed by two rays with a
common endpoint. In the figure, ∠RST is
formed by
and
with the common
𝑆𝑅
𝑆𝑇
endpoint (or vertex) S.
• Side--The two rays that
form an angle.
• Vertex--The common endpoint of the rays
forming the angle.
Angles and Their Parts
A. Name all angles that
have B as a vertex.
Answer:
Angles and Their Parts
B. Name the sides of 5.
Answer:
Angles and Their Parts
C.
A.
A.
B.
C.
D.
A.
B.
C.
D.
A
B
C
D
B.
A.
B.
C.
D. none of these
A.
B.
C.
D.
A
B
C
D
C. Which of the following is another name for 3?
A.
B.
C.
D.
A.
B.
C.
D.
A
B
C
D
Degreee--The most common unit of measure for angles. If a circle were
divided into 360 equal-sized parts, each part would have an angle
measure of 1 degree, denoted as 1°.
Measure and Classify Angles
A. Measure TYV and classify it as right, acute,
or obtuse.
Answer: mTYV = 90, so TYV is a right angle.
Measure and Classify Angles
Answer: 180 > mWYT > 90,
so WYT is an obtuse angle.
Measure and Classify Angles
A. Measure CZD and classify
it as right, acute, or obtuse.
A. 30°, acute
B. 30°, obtuse
C. 150°, acute
D. 150°, obtuse
A.
B.
C.
D.
A
B
C
D
B. Measure CZE and classify
it as right, acute, or obtuse.
A. 60°, acute
B. 90°, acute
C. 90°, right
D. 90°, obtuse
A.
B.
C.
D.
A
B
C
D
C. Measure DZX and classify
it as right, acute, or obtuse.
A. 30°, acute
B. 30°, obtuse
C. 150°, acute
D. 150°, obtuse
A.
B.
C.
D.
A
B
C
D
• Bisect an angle
• Bisect--To separate something into two
congruent parts.
Measure and Classify Angles
INTERIOR DESIGN Wall stickers of standard shapes
are often used to provide a stimulating environment
for a young child’s room. A five-pointed star sticker
is shown with vertices labeled. Find mGBH and
mHCI if GBH  HCI, mGBH = 2x + 5, and
mHCI = 3x – 10.
Measure and Classify Angles
Step 1 Solve for x.
GBH  HCI
mGBH  mHCI
2x + 5 = 3x – 10
2x + 15 = 3x
15 = x
Given
Definition of congruent angles
Substitution
Add 10 to each side.
Subtract 2x from each side.
Measure and Classify Angles
Step 2 Use the value of x to find the measure of
either angle.
.
Answer: mGBH = 35, mHCI = 35
Find mBHC and mDJE if BHC  DJE,
mBHC = 4x + 5, and mDJE = 3x + 30.
A. mBHC = 105, mDJE = 105
B. mBHC = 35, mDJE = 35
C. mBHC = 35, mDJE = 105
D. mBHC = 105, mDJE = 35
A.
B.
C.
D.
A
B
C
D