WAEC Further Mathematics Past Questions & Answers - Page 105

521.

Express (14N, 240°) as a column vector.

A.

\(\begin{pmatrix} -7 \\ -7\sqrt{3} \end{pmatrix}\)

B.

\(\begin{pmatrix} 7\sqrt{3} \\ 7\sqrt{3} \end{pmatrix}\)

C.

\(\begin{pmatrix} -7\sqrt{3} \\ -7 \end{pmatrix}\)

D.

\(\begin{pmatrix} 7 \\ -7\sqrt{3} \end{pmatrix}\)

Correct answer is A

\(F = \begin{pmatrix} F_{x} \\ F_{y} \end{pmatrix} = \begin{pmatrix} F\cos \theta \\ F\sin \theta \end{pmatrix}\)

\((14N, 240°) = \begin{pmatrix} 14\cos 240 \\ 14\sin 240 \end{pmatrix}\)

= \(\begin{pmatrix} 14 \times -0.5 \\ 14 \times \frac{-\sqrt{3}}{2} \end{pmatrix}\)

= \(\begin{pmatrix} -7 \\ -7\sqrt{3} \end{pmatrix}\)

522.

Evaluate \(\frac{\tan 120° + \tan 30°}{\tan 120° - \tan 60°}\)

A.

\(\sqrt{3} + \sqrt{2}\)

B.

\(\frac{2}{3}\)

C.

\(\frac{1}{3}\)

D.

\(-2\sqrt{3}\)

Correct answer is C

No explanation has been provided for this answer.

523.

Find \(\lim\limits_{x \to 3} (\frac{x^{3} + x^{2} - 12x}{x^{2} - 9})\)

A.

\(\frac{7}{2}\)

B.

\(0\)

C.

\(\frac{-7}{2}\)

D.

\(-7\)

Correct answer is A

\(\lim\limits_{x \to 3} (\frac{x^{3} + x^{2} - 12x}{x^{2} - 9}) = \lim\limits_{x \to 3} (\frac{x^{3} - 3x^{2} + 4x^{2} - 12x}{(x - 3)(x + 3)}\)

\(\lim\limits_{x \to 3} (\frac{(x^{2} + 4x)(x - 3)}{(x - 3)(x + 3)} = \lim\limits_{x \to 3} (\frac{x^{2} + 4x}{x + 3})\)

=\(\frac{3^{2} + 4(3)}{3 + 3} = \frac{21}{6} = \frac{7}{2}\)

524.

Find the distance between the points (2, 5) and (5, 9).

A.

4 units

B.

5 units

C.

12 units

D.

14 units

Correct answer is B

Distance between two points (a, b) and (c, d) = \(\sqrt{(d - b)^{2} + (c - a)^{2}}

Distance between (2, 5) and (5, 9) = \(\sqrt{(9-5)^{2} + (5-2)^{2}}\)

= \(\sqrt{16 + 9} = \sqrt{25} = 5 units\)

525.

A ball is thrown vertically upwards with a velocity of 15\(ms^{-1}\). Calculate the maximum height reached. \([g = 10ms^{-2}]\)

A.

15.25m

B.

13.25m

C.

11.25m

D.

10.25m

Correct answer is C

Maximum height (H) = \(\frac{u^{2}}{2g}\)

= \(\frac{15^{2}}{2 \times 10} = \frac{225}{20}\)

= \(11.25m\)