CAIE IGCSE Additional Math 7.2 Use Parallel and Perpendicular Gradients Questions

Practise Cambridge IGCSE Additional Mathematics by using perpendicular gradients to determine straight-line equations.

Exam points

Use the negative reciprocal gradient relationship for perpendicular lines.
Determine the equation of a line in gradient-intercept form from a point and gradient.
Check the resulting line satisfies the given point and perpendicularity conditions.

[Maximum number: 4]

The coordinates of points A and B are (-5,6) and (4,-6) respectively. The point C lies on the line AB, between A and B, such that $\frac{AC}{CB}=\frac12$ .

The line CD is perpendicular to AB. Find the equation of CD in the form y=mx+c.

$m_{AB}=\frac{-6-6}{4-(-5)}=-\frac43$ $m_{CD}=\frac34$ $y-2=\frac34(x+2)$ $y=\frac34x+\frac72$

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CAIE IGCSE Additional Math 7.2 Use Parallel and Perpendicular Gradients Questions question 1