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Broad Topics > 2D Geometry, Shape and Space > Perpendicular lines

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At Right Angles

Stage: 3 Challenge Level: Challenge Level:2 Challenge Level:2

Can you decide whether two lines are perpendicular or not? Can you do this without drawing them?

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Perpendicular Lines

Stage: 3 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

Position the lines so that they are perpendicular to each other. What can you say about the equations of perpendicular lines?

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Angle Trisection

Stage: 4 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

It is impossible to trisect an angle using only ruler and compasses but it can be done using a carpenter's square.

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Flexi Quads

Stage: 5 Challenge Level: Challenge Level:1

A quadrilateral changes shape with the edge lengths constant. Show the scalar product of the diagonals is constant. If the diagonals are perpendicular in one position are they always perpendicular?

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Orthogonal Circle

Stage: 5 Challenge Level: Challenge Level:2 Challenge Level:2

Given any three non intersecting circles in the plane find another circle or straight line which cuts all three circles orthogonally.

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Sorting Letters

Stage: 1 and 2 Challenge Level: Challenge Level:1

This interactivity allows you to sort letters of the alphabet into two groups according to different properties.

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Dotty Relationship

Stage: 2 Challenge Level: Challenge Level:2 Challenge Level:2

Can you draw perpendicular lines without using a protractor? Investigate how this is possible.

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Right Angle Challenge

Stage: 1 Challenge Level: Challenge Level:2 Challenge Level:2

How many right angles can you make using two sticks?

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Walls

Stage: 5 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

Plane 1 contains points A, B and C and plane 2 contains points A and B. Find all the points on plane 2 such that the two planes are perpendicular.

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A Shade Crossed

Stage: 4 Challenge Level: Challenge Level:1

Find the area of the shaded region created by the two overlapping triangles in terms of a and b?

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The Dodecahedron Explained

Stage: 5

What is the shortest distance through the middle of a dodecahedron between the centres of two opposite faces?

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What Are You Plotting?

Stage: 2 Challenge Level: Challenge Level:1

Investigate the positions of points which have particular x and y coordinates. What do you notice?

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Similarly So

Stage: 4 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

ABCD is a square. P is the midpoint of AB and is joined to C. A line from D perpendicular to PC meets the line at the point Q. Prove AQ = AD.

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Tricircle

Stage: 4 Challenge Level: Challenge Level:2 Challenge Level:2

The centre of the larger circle is at the midpoint of one side of an equilateral triangle and the circle touches the other two sides of the triangle. A smaller circle touches the larger circle and. . . .

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Right Time

Stage: 3 Challenge Level: Challenge Level:2 Challenge Level:2

At the time of writing the hour and minute hands of my clock are at right angles. How long will it be before they are at right angles again?

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Shrink

Stage: 4 Challenge Level: Challenge Level:2 Challenge Level:2

X is a moveable point on the hypotenuse, and P and Q are the feet of the perpendiculars from X to the sides of a right angled triangle. What position of X makes the length of PQ a minimum?

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Quads

Stage: 4 and 5 Challenge Level: Challenge Level:2 Challenge Level:2

The circumcentres of four triangles are joined to form a quadrilateral. What do you notice about this quadrilateral as the dynamic image changes? Can you prove your conjecture?

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Three Way Split

Stage: 4 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

Take any point P inside an equilateral triangle. Draw PA, PB and PC from P perpendicular to the sides of the triangle where A, B and C are points on the sides. Prove that PA + PB + PC is a constant.

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Square World

Stage: 5 Challenge Level: Challenge Level:1

P is a point inside a square ABCD such that PA= 1, PB = 2 and PC = 3. How big is angle APB ?