3-21. For each diagram below, solve for x. Explain what angle properties or relationship(s) you used for each problem.

Answer:
a. x = 8°
b. x = 20°
Step-by-step explanation:
a. 6x + 4x + 10 = 90 (this is complimentary and this is because there is a small square which indicates that it is 90 degrees)
10x = 90 - 10
10x = 80
x = 8°
b. 5x + 13 + 3x + 7 = 180 (supplementary. Straight lines add up to 180°)
8x = 180 - 7 - 13
8x = 160
x = 20°
The values of x in the diagrams obtained using the triangle theorem are 8 and 20 respectively
Triangle 1 :
The angle formed is right angled, hence it has a total of 90°
6x + (4x + 10) = 90°
6x + 4x + 10 = 90
10x + 10 = 90
10x = 90 - 10
10x = 80
x = 80/10
x = 8
Triangle 2 :
Sum of angles on a straight line = 180°
(5x + 13) + (3x + 7) = 180°
5x + 3x + 13 + 7 = 180°
8x + 20 = 180°
8x = 180 - 20
8x = 160
x = 160 / 8
x = 20°
Therefore, the values of X are 8 and 20 respectively.
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