WAEC - Mathematics (1995 - No. 38)
In the diagram above, the value of angles b + c is
180o
90o
45o
ao
do
توضیح
a + c + d = 180o[sum of angles in triangle]
x = a[vertical opp. ∠s]
y + x + d = 180o[sum of ∠s in a Δ]
y + a + d = 180o
y + a + d = a + c + d
y = c
but b + y = 180o [sum of ∠s on a straight line ]
b + c = 180o; Ans = A = 180o