5a. a° = 128°
5b. b° = 1.3°
5c. c° = 341°
How to determine the unknown sides
5a
a° = 128°
This is because parallel angles are equal and angles a° and 128° are parallel to each other
5b
Angles (4b-10)° and (2b - 2)° are equal.
This is because alternate angles are equal and they are alternate to each other
To find b , equate both angles
4b - 10 = 2b - 2
collect like terms
4b + 2b = -2 + 10
6b = 8
Make 'b' subject of formula
b = 8/6
b = 1.3°
5c.
c° is at angle at a point.
19° is alternate to the other part of the point
We have, c° + 19° = 360° (angle at a point)
c° + 19° = 360°
Make 'c' subject of formula
c° = 360° - 19°
c° = 341°
Thus, the unknown angles are given as a = 128°, b = 1.3°, c = 341°
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