A regular polygon has 150º as the size of each interior angle. How many sides does it have?
12
10
9
8
Correct answer is A
Sum of interior angles of a polygon = each interior ∠ x n
(n-2)180 = 150 x n
180n - 360 = 150n
180n-150n = 360
30n = 360
n = 360/30
n = 12 sides
Find the acute angle between the straight lines y = x and y = √3x
15o
30o
45o
60o
Correct answer is A
y = x, Gradient (m1) = 1
y = √3x gradient (m2) = √3
\(tan\theta = \frac{m_2 - m_1}{1+m_2 m_1}\\
tan\theta = \frac{\sqrt{3}-1}{1+\sqrt{3}\times 1}\\
=\frac{1.73 -1 }{1+1.73}=
\frac{0.73}{2.73}=0.268\)
θ = Tan-1 (0.268)
= 15o
If P \(=\left[\begin{array}{cc}x+3 & x+2\\
x+1 & x-1\end{array}\right]\) evaluate x if |P| = -10
-5
-2
2
5
Correct answer is D
\(P=\left[\begin{array}{cc}x+3 & x+2\\
x+1 & x-1\end{array}\right]\) evaluate x if |P| = -10
(x+3)(x-1) - {(x+1)(x+2)} = -10
x2 - x + 3x - 3 - {x2 + 2x + x + 2} = -10
x2 + 2x - 3 - {x2 + 3x + 2} = -10
-x - 5 = -10
-5 + 10 = x
5 = x
∴x = 5
If Q is\( \left[ \begin{array}{cc}
9 & -2 \\
-7 & 4 \\
\end{array} \right]\) , then |Q| is?
-50
-22
22
50
Correct answer is C
Q = \( \left[ \begin{array}{ccc}
9 & -2 \\
-7 & 4 \\
\end{array} \right]\)
|Q| = 9x4 - (-2x7)
= 36 - 14
= 22
-5/4
-5/6
zero
5
Correct answer is A
\(m \otimes n = m + n + mn\)
Let the inverse of -5 be n.
\(\therefore -5 \otimes n = 0\)
\(-5 + n + (-5n) = 0\)
\(n - 5n = 5 \implies -4n = 5\)
\(n = -\frac{5}{4}\)