Apps. and Interpretation for IBDP Maths Ebook 1 | Page 114

Your Practice Set – Applications and Interpretation for IBDP Mathematics
32
Paper 2 – Areas Bounded by Straight Lines
Example
The straight line L
1
passes through the points A( � 15, 0) and B(0, 20) .
(a) Find the gradient of L
1
.
(b) Find the equation of L
1
, giving the answer in general form.
Another straight line L
2
passes through the origin O and is perpendicular to L
1
.
[2]
[3]
(c) Find the equation of L
2
, giving the answer in slope-intercept form.
L
1
and L
2
intersects at the point C .
(d) Find the coordinates of C .
(e) Find the area of the triangle OBC .
(f) Find the perimeter of the triangle OBC .
[2]
[3]
[2]
[4]
Solution
(a) The gradient of L
1
0 � 20
� (M1) for valid approach
� 15 � 0
4
� A1 N2
3
(b) The equation of L
1
:
4
y� 20 � ( x� 0)
3
(M1) for substitution
3y�60 � 4x
(A1) for simplification
4x�3y� 60 � 0
A1 N3
[2]
[3]
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