CAIE
FP1
2013
June
Q11 OR
Standard +0.8
The points \(A , B , C\) and \(D\) have coordinates as follows:
$$A ( 2,1 , - 2 ) , \quad B ( 4,1 , - 1 ) , \quad C ( 3 , - 2 , - 1 ) \quad \text { and } \quad D ( 3,6,2 ) .$$
The plane \(\Pi _ { 1 }\) passes through the points \(A , B\) and \(C\). Find a cartesian equation of \(\Pi _ { 1 }\).
Find the area of triangle \(A B C\) and hence, or otherwise, find the volume of the tetrahedron \(A B C D\).
[0pt]
[The volume of a tetrahedron is \(\frac { 1 } { 3 } \times\) area of base × perpendicular height.]
The plane \(\Pi _ { 2 }\) passes through the points \(A , B\) and \(D\). Find the acute angle between \(\Pi _ { 1 }\) and \(\Pi _ { 2 }\).
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CAIE
FP1
2013
June
Q2
6 marks
Challenging +1.2
2 The roots of the equation \(x ^ { 4 } - 4 x ^ { 2 } + 3 x - 2 = 0\) are \(\alpha , \beta , \gamma\) and \(\delta\); the sum \(\alpha ^ { n } + \beta ^ { n } + \gamma ^ { n } + \delta ^ { n }\) is denoted by \(S _ { n }\). By using the relation \(y = x ^ { 2 }\), or otherwise, show that \(\alpha ^ { 2 } , \beta ^ { 2 } , \gamma ^ { 2 }\) and \(\delta ^ { 2 }\) are the roots of the equation
$$y ^ { 4 } - 8 y ^ { 3 } + 12 y ^ { 2 } + 7 y + 4 = 0$$
State the value of \(S _ { 2 }\) and hence show that
$$S _ { 8 } = 8 S _ { 6 } - 12 S _ { 4 } - 72 .$$
CAIE
FP1
2013
June
Q8
11 marks
Challenging +1.2
8 The curve \(C\) has parametric equations \(x = \frac { 3 } { 2 } t ^ { 2 } , y = t ^ { 3 }\), for \(0 \leqslant t \leqslant 2\). Find the arc length of \(C\).
Find the coordinates of the centroid of the region enclosed by \(C\), the \(x\)-axis and the line \(x = 6\).
CAIE
FP1
2014
June
Q9
10 marks
Standard +0.3
9 The matrix \(\mathbf { M }\), where
$$\mathbf { M } = \left( \begin{array} { r r r }
- 2 & 2 & 2 \\
2 & 1 & 2 \\
- 3 & - 6 & - 7
\end{array} \right)$$
has an eigenvector \(\left( \begin{array} { r } 0 \\ 1 \\ - 1 \end{array} \right)\). Find the corresponding eigenvalue.
It is given that if the eigenvalues of a general \(3 \times 3\) matrix \(\mathbf { A }\), where
$$\mathbf { A } = \left( \begin{array} { l l l }
a & b & c \\
d & e & f \\
g & h & i
\end{array} \right)$$
are \(\lambda _ { 1 } , \lambda _ { 2 }\) and \(\lambda _ { 3 }\) then
$$\lambda _ { 1 } + \lambda _ { 2 } + \lambda _ { 3 } = a + e + i$$
and the determinant of \(\mathbf { A }\) has the value \(\lambda _ { 1 } \lambda _ { 2 } \lambda _ { 3 }\).
Use these results to find the other two eigenvalues of the matrix \(\mathbf { M }\), and find corresponding eigenvectors.