Sewanhaka High School
Mrs. Lidowsky, Principal
Math 8
Mr. Long, Teacher
Class:________________
Date:_____________________
Name:________________________________
H.W. #69E: Ditto
DO-NOW #69E: Answer the following questions:
1) Measure the following angle and find its complement and supplement:
Name the angle three ways:
Name the rays:
Measure of Angle:
What type of angles is this?
S
U
B
2) Simplify the expression: 3x(4x + 7) =
Topic: Geometry with ALGEBRA
Main Idea: Complementary Angles
Aim:
Recall
Refer to the picture to the
left. What type of angle
is that called?
Without the use of a
protractor, what is the
clue that tells us that the
picture is a right angle?
What if we broke up the
right angle into two
angles that are next to
each other? What do we
know about those
angles?
What do we call two
angles that are next to
each other that equal
90°?
Answer: complementary
angles
Question: Give an
example.
Question: Given the following angles, find their complements:
a) 23°
b) 10°
c) 64°
d) x
e) 3x
f) x + 10
Notes
What if they told you that one angle is 10° more than its
complement. How would you find the measure of both
angles algebraically?
The ratio of the measure of an angle to the measure of
its complement is 2:3. Find the measure of the angle
and the measure of its complement.
<ABD is a right angle. Find the m<ABC and m<CBD.
A
C
8x
x
B
D
Drill: Answer the following questions:
1) One angle is 20° less than its complement. How would you find both angles?
2) The ratio of the measure of an angle to the measure of its complement is 2:4. Find the measure of the
angle and the measure of its complement.
3) <ABD is a right angle. Find the m<ABC, m<CBE, and m<EBD.
A
C
E
2x
x
x + 30
B
Summary:
D