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Name: __________________________________________
Geometry A Unit 1 Day 1 Finding Missing Angles
Date: ___________________
Goal: I can find missing angles HW: Finding Missing Angles
Upcoming Events:
on a line and around a point.
Directions: Use your Unit 1 Reference Guide to help you answers the questions below.
1) What type of angle measures 90°?
a) Supplementary
b) Complementary
c) Right
D) Straight
2) If 12x = 4(x + 3) then x equals
a) 1.5
b)
3
8
c) 5
d)
12
11
3) Which statement represents the relationship between angles x and y in the diagram
below?
a) x + y = 90
x
b) x + y = 180
c) x = y
1
d) y = x
y
2
4) In the diagram to the right 2 rays and a line intersect at a
point. Which of the following pairs of angles are a linear pair?
a) ∠1 and ∠3
c) ∠1 and ∠4
b) ∠2 and ∠3
d) ∠3 and ∠4
5) Which of the following statement most accurately
describes angles c and d below?
d
c
a) Angles c and d are congruent because vertical angles are congruent.
b) Angles c and d add to 180° because vertical angles are congruent.
c) Angles c and d are congruent because supplementary angles are congruent.
d) Angles c and d add to 180° because supplementary angles add to 180°
6) Which of the angle pairs below can be classified as complementary?
a) 80° and 20°
b) 80° and 100°
c) 80° and 10°
d) 80° and 280°
The sum of angles on a straight line is 180°.
In the figure, 𝐴𝐵 is a straight line.
Find the measure of ∠𝑓.
∠𝑓 =
𝐴
𝐵
The sum of adjacent angles around a point is 360°.
Find the measure of ∠𝑔.
∠𝑔 =
Vertical angles have
Find the measure of ∠ℎ.
∠ℎ =
measure.
Example 1
Find the measures of each labeled angle. Give a reason for your
solution.
Angle
a
b
c
d
e
Angle
measure
Justification
Statement
Reason
97 + b + 36 = 180
Angles on a straight line = 180°
133 + b = 180
Combine Like Terms
b = 47
Subtraction
Example 2
Exercises
Directions: In the figures below, 𝐴𝐵, 𝐶𝐷, and 𝐸𝐹 are straight lines. Find the measure of each marked angle
or find the unknown numbers labeled by the variables in the diagrams. Give reasons for your calculations.
Show all the steps to your solution.
1.
2.
Statements
Reasons
Statements
Reasons
∠𝑍𝑀𝐵 = 90°
Y
Right angles measure 90°
Z
X
M
Example 3
Statements
Reasons
g + g + g + 91 + 91
+ 91 = 360
Angles around a point equal 360°
3g + 273 = 360
Combine Like Terms
3g = 87
Subtraction
g = 29
Division
Directions: For the questions below SHOW ALL WORK to find the missing angles.
𝑥=
4.
𝑦 = ___________
5.
3x + 6
𝑥=
𝑦 = ___________
x - 11
x - 10
y
6.
𝑥=
y
3
x—2
4
2
x
5
𝑦 = __________
Name: __________________________________________
Geometry CC Unit 1 Day 1 Finding Missing Angles HOMEWORK
1.
Date: ______________
Statements
Reasons
Statements
Reasons
2.
Directions: For the questions below SHOW ALL WORK to find the missing angles.
3.
4.
𝑥 = ___________
𝑥 = _________
𝑦 = _________
5.
𝑥 = ___________
6.
𝑥=
𝑦 = ____________
7.
𝑥=
2x + 1
3x + 10
8
x + 10
9
y—3
y
𝑦 = ___________