2008 - WAEC Mathematics Past Questions and Answers - page 5
41
If the perimeter of \(\bigtriangleup\)PQR in thr diagram is 24cm, what is the area of \(\bigtriangleup\)PRS?
A
19.5cm2
B
15.0cm2
C
13.0cm2
D
9.3cm2
correct option: b
Perimeter of \(\bigtriangleup\) PQR = PQ + QR + PR
24cm = 6cm + 8cm = PR
24 = 14 + PR
PR = 24 - 14 = 10cm
Area of \(\bigtriangleup\) PRS = \(\frac{1}{2} \times 10 \times 3cm^3\)
= 15cm3
Users' Answers & Comments24cm = 6cm + 8cm = PR
24 = 14 + PR
PR = 24 - 14 = 10cm
Area of \(\bigtriangleup\) PRS = \(\frac{1}{2} \times 10 \times 3cm^3\)
= 15cm3
42
In the diagram, PX is a tangent to the circle and RST is an equilateral triangle. Calculate < PTS
A
60o
B
90o
C
120o
D
150o
correct option: c
\(\bigtriangleup\) RST is equilateral triangle, hence
< TRS = < RTS = < RSt = 60o
But < PTR = 60o(Angle between a chord and a tangent at the point of contact = Angle in the alt. segment). From the diagram < PTS = < PTR + < RTS
= 60o + 60o = 120o
Users' Answers & Comments< TRS = < RTS = < RSt = 60o
But < PTR = 60o(Angle between a chord and a tangent at the point of contact = Angle in the alt. segment). From the diagram < PTS = < PTR + < RTS
= 60o + 60o = 120o
43
In the diagram, < QPR = 60o
< PQR = 50o
< QRS = 2xo
< SRP = 3xo
< UQP = yo and RS//TU
calculate y
< PQR = 50o
< QRS = 2xo
< SRP = 3xo
< UQP = yo and RS//TU
calculate y
A
102o
B
78o
C
70o
D
60o
correct option: a
< RQT = < QRS = 2x (Alternate angles). But in \(\bigtriangleup\) PRQ
50 + 60 + (2x + 3x) = 180o(Angles in a triangle)
110 + 5x = 180o
5x = 180o - 110 = 70o
x = \(\frac{70}{5}\) = 14o
Also y + 50 + 2(14) = 180o
y + 50 + 28 = 180o
y = 180 - 78
y = 102o
Users' Answers & Comments50 + 60 + (2x + 3x) = 180o(Angles in a triangle)
110 + 5x = 180o
5x = 180o - 110 = 70o
x = \(\frac{70}{5}\) = 14o
Also y + 50 + 2(14) = 180o
y + 50 + 28 = 180o
y = 180 - 78
y = 102o
44
In the diagram, find the size of the angle marked a°
A
60o
B
80o
C
120o
D
160o
correct option: b
2 x s = 280°(Angle at centre = 2 x < at circum)
S = \(\frac{280^o}{2}\)
= 140°
< O = 360 - 280 = 80°
60 + 80 + 140 + a = 360°
(< in a quad); 280 + a = 360
a = 360 - 280
a = 80°
45
Every staff in an office owns either a Mercedes and/or a Toyota car. 20 own Mercedes, 15 own Toyota and 5 own both. How many staff are there in the office?
A
25
B
30
C
35
D
45
correct option: b
M = Mercedez; T = Toyota
Number of staff = 0 + (20 - 5) + (15 - 5) + 5
0 + 15 + 10 + 5 = 30
Users' Answers & CommentsNumber of staff = 0 + (20 - 5) + (15 - 5) + 5
0 + 15 + 10 + 5 = 30