Answer:
a = 7
b = 7
c = 14 [Correct option is B. 14]
Step-by-step explanation:
Since the shape is a parallelogram, to solve this problem, use some of the properties of a parallelogram:
(i) Opposite sides are parallel and congruent. Being congruent means the sides are identical. In other words, they have the same length.
From the diagram, this means that sides PQ and SR are identical. i.e
=> PQ = SR
=> 6a + 10 = 8a - 4 [collect like terms and solve]
=> 14 = 2a
=> a = 7
(ii) Opposite angles are congruent. Angles PQR and PSR are identical. i.e
<PQR = <PSR = (9b + 2)°
Also,
<SPQ = <SRQ = (18b - 11)°
(iii) Consecutive angles are supplementary. The sum of any two angles that are not opposite to each other is 180°. i.e.
<SPQ + <PQR = 180°
<PQR + <QRS = 180°
<QRS + <RSP = 180°
.
.
.
Also,
<PSR + <SPQ = 180°
(9b + 2)° + (18b - 11)° = 180° [expand bracket and solve for b]
9b + 2 + 18b - 11 = 180
27b - 9 = 180
27b = 189
b = 7
Now, since a = 7 and b = 7;
c = a + b = 7 + 7 = 14
Therefore;
a = 7
b = 7
c = 14
