Supplementary
Angles
Definition:
Supplementary angles are sum of a two adjacent angles (two angles having a common vertex and sharing one side) with a total measure of 180°. Supplementary angles have a non-sharing side and these sides will form a linear pair.
Introduction:
- Supplementary angles are formed by combining one acute angle and one obtuse angle. (Fig. 1)
- Supplementary angles are also formed by combining two right angles. (Fig. 2)
Figure 2. If two right angles are combined, it will form a supplementary angle.
Formula:
Finding the sum of the two angles:
m ∠x + m ∠y = 180°
If an
angle is missing the formula is:
(missing
angle) = 180° - (the given angle)
Examples:
1) Find the
sum of m ∠ABC and m ∠CBD.
Write the given:
m∠ABC = 127
m∠CDF = 53
Write the formula:
m
∠ABC + m ∠CDF =
180°
Substitute: 127 + 53= 180°
Solve: 180° = 180°
Answer: 180°
2) Find the missing angle.
Write the
given:
m∠CJA = 144
m∠AJD = ?
Write the formula: m∠AJD= 180°- m∠CJA
Substitute: m∠AJD = 180° -
144
Solve:
m∠AJD =
36°
Answer 36°
Reference:
Mendoza, M.,
& Oronce, O., 2003. Exploring Mathemetics: Goemetry III(First edition). P.
Florentino St., Sta. Mesa Heights, Quezon City: Rex Printing Company, Inc.
Submitted to: Professor Crisencio M. Paner, MSc.
