CAIE IGCSE Mathematics Extended E3.7.1 Find the Gradient and Equation of a Straight Line Perpendicular to a Questions

Practise Extended CAIE IGCSE Mathematics by using negative reciprocal gradients and points to form perpendicular-line equations.

Exam points

Use the negative reciprocal gradient relationship for perpendicular lines.
Find the equation of a line perpendicular to a given line through a specified point.
Check perpendicularity using the product of gradients or equivalent geometry.

[Maximum number: 4]

16 A is the point (7,2) and B is the point (-5,8).

Find the equation of the line that is perpendicular to AB and that passes through the point (-1,3). Give your answer in the form y=m x+c.

y=2x+5 final answer

M1 for gradient of $AB=\frac{8-2}{-5-7}$ oe.
M1 for gradient of perpendicular, $p=-\frac{1}{\text{their gradient}}$ oe.
M1 dep for substituting (-1,3) into $y=\text{their }px+c$ , where their $p\ne0$ .

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CAIE IGCSE Mathematics Extended E3.7.1 Find the Gradient and Equation of a Straight Line Perpendicular to a Questions question 1