WAEC Mathematics Past Questions & Answers - Page 270

1,346.

In ΔABC above, BC is produced to D, /AB/ = /AC/ and ∠BAC = 50o. Find ∠ACD

A.

50o

B.

60o

C.

65o

D.

100o

E.

115o

Correct answer is E

ACB = ABC [Base angles of isoceles triangle]
ACB + ABC + 50o = 180o[sum of angles in a triangle]
ACB + ABC = 180o - 50o = 130o

ACB
130o/2
= 65o

ACD + ACB = 180o[sum of ∠s on a straight line]
ACD + 65o = 180o
ACD = 180o - 65o = 115o

1,347.

Which of the following angles is an exterior angle of a regular polygon?

A.

95o

B.

85o

C.

78o

D.

75o

E.

72o

Correct answer is E

The formula for the exterior angle of a regular polygon = \(\frac{360}{n}\).

Among the options, only 72° is divisible by 360° to give an integer.

1,348.

In the diagram above, the value of angles b + c is

A.

180o

B.

90o

C.

45o

D.

ao

E.

do

Correct answer is A

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

1,349.

The locus of a point which is equidistant from two given fixed points is the

A.

Perpendicular bisector of the straight line joining them

B.

Angle bisector of the straight lines joining the points to the origin

C.

Perpendiculars to the straight line joining them

D.

Parallel-line to the straight line joining them

E.

A line making an acute angle with the line joining the two points

Correct answer is A

No explanation has been provided for this answer.

1,350.

In the diagram above, AB//CD, the bisector of ∠BAC and ∠ACD meet at E. Find the value of ∠AEC

A.

30o

B.

45o

C.

60o

D.

75o

E.

90o

Correct answer is E

Ae is a bisector of BAC => EAC = 45o
CE is the bisector of ACD => ACE = 45o
AEC = 180o - [EAC + ACE]
    = 180o - (45o + 45o) = 180o - 90o = 90o