1991 - WAEC Mathematics Past Questions and Answers - page 3

21

Find the coordinates of point B

A
(0,11/2)
B
(O,2)
C
(2,0)
D
(11/2, 2)
correct option: e

B occurs at the point y = 0. 

When y = 0, we have

4x + 3(0) = 6

4x = 6

x = 1\(\frac{1}{2}\)

B = \((1\frac{1}{2}, 0)\)

Users' Answers & Comments
22
The first term a of an A.P is equal to twice the
common difference d. Find, in terms of d, the 5th
term of the A.P.
A
4d
B
5d
C
6d
D
a + 5d
correct option: c
Tn = a + (n - 1)d; AP; a = 2d; Tn = 2d + (n - 1)d

T5 = 2d + (5 - 1)d = 2d + 4d = 6d
Users' Answers & Comments
23
The common ratio of a G.P. is 2. If the 5th term is
greater than the 1st term by 45, find the 5th term,
A
3
B
6
C
45
D
48
correct option: d
a = 1st term ; ar4 = 5th term
∴ ar4 = a(2)4 = 16a; 16a = 45 + a, a = 3;
3(2)4 = 48
Users' Answers & Comments
24
Two towns, P and Q, are on (4oN 40oW) and (4oN
20oE) respectively. What is the distance between
them, along their line of latitude? (Give your
answer in teems of π and R, the radius of the earth).
A
2πR cos4o
B
πR sin40o
C
πR/2
cos4o
D
πR/3
cos4o
correct option: d
Angular distance = 40o + 20o = 60o
using θ/360 x 2πr for distance between p and Q
= 60/360 x 2πRcos4o = 1/3πRcos4o
Users' Answers & Comments
25
the graph above is a sketch of
A
y = sin 2x
B
y=sinx
C
y=cos2x
D
y=2sinx
correct option: d
Users' Answers & Comments
26

Given that sin \(\theta\) = -0.9063, where O \(\leq\) \(\theta\) \(\leq\) 270°, find \(\theta\).

A
65o
B
115o
C
145o
D
245o
correct option: d

Sin\(\theta\) = -0.9063; \(\theta\) = sin-1(0.9063)

\(\theta\) = -64.99 = -65°

\(\theta\) = 180° - (-65);

180 + 65 = 245°

Users' Answers & Comments
27
From the top of a cliff, the angle of depression of
a boat on the sea is 60o, if the top of the cliff is
25m above the sea level, calculate the horizontal
distance from the bottom of the cliff to the boat.
A
50√3m
B
25√3m
C
25√3m/3
D
25m/3
correct option: c
x/25 = tan 30o
x =
25/√3 =
25√3/3
Users' Answers & Comments
28
The angle of elevation of the top of a tree 39m
away from a point on the ground is 30o. Find the height of the tree
A
39√3m
B
13√3m
C
13/\(\sqrt{3}\)m
D
13/3\(\sqrt{3}\)m
correct option: b
x/25 = tan 30o
x = 39 x 1/√3 = 13√3m
Users' Answers & Comments
29

In the diagram above, ATR is a tangent at the point T to the circle center O, if ∠TOB = 145°, find ∠TAO

A
20o
B
35o
C
45o
D
55o
correct option: d

From the figure, < ATO = 90°

< AOT = 180° - 145° = 35°

\(\therefore\) < TAO = 180° - (90° + 35°)

= 55° (sum of angle in a triangle)

Users' Answers & Comments
30

P={2, 1,3, 9, 1/2}; Q = {1,21/2,3, 7} and R = {5, 4, 21/2}. Find P∪Q∪R

A
(21/2)
B
(1, 9)
C
(1, 2, 3, 4, 5, 6, 7)
D
(5, 4, 21/2)
correct option: e

P = {2,1,3,9,1/2}; Q = {1,21/2,3,7}
R = {5,4,212}
P∪Q∪R = {1/2,1,2,21/2,3,4,5,7,9}

= {1/2,1,2,21/2,3,4,5,7,9}

Users' Answers & Comments
Please share this, thanks: