Question:
In the below Fig. OA and OB are opposite rays:
(i) If x = 25, what is the value of y?
(ii) If y = 35, what is the value of x?
Solution:
(i) Given that,
x = 25
Since ∠AOC and ∠BOC form a linear pair
∠AOC + ∠BOC = 180°
Given that ∠AOC = 2y + 5 and ∠BOC = 3x
∠AOC + ∠BOC = 180°
(2y + 5) + 3x = 180
(2y +5) + 3(25) = 180
2y + 5 + 75 = 180
2y + 80 = 180
2y = 180 - 80 = 100
y = 100/2 = 50
y = 50
(ii) Given that,
y = 35
∠AOC + ∠BOC = 180°
(2y + 5) + 3x = 180
(2(35) + 5) + 3x = 180
(70 + 5) + 3x = 180
3x = 180 - 75
3x = 105
x = 35