Answer:
Step-by-step explanation:
Q13
The greater the angle the greater the opposite side
Sides in ascending order:
- AB = 17, AC = 18, BC = 21
Angles in same order
Q14
As above, sides in ascending order:
- AB = 15, AC = 16, BC = 17
Angles in same order
Q15
Exterior angle equals to sum of non-adjacent interior angles
- 142° = x + 66°
- x = 142° - 66°
- x = 76°
Q16
Same subject and isosceles triangle:
- x + x = 158°
- 2x = 158°
- x = 79°
Q17
Same subject
- m∠QSR = m∠QPS + m∠PQS
- 2x = x + m∠PQS
- m∠PQS = 2x - x
- m∠PQS = x
ΔPQS has two angles with the measure of x, hence their opposite sides are congruent and the triangle is isosceles
