**"Triangles"**

## Grades 4 to 8 Making Triangles

*By toni On 12 November, 2017 · Leave a Comment*

Use 11 sticks of equal length to make this triangle with edge lengths 2, 4 and 5. You might like to record this as (2, 4, 5).

How many other triangles can you make with 11 sticks?

Investigate all the triangles that you can make with different numbers of sticks.

Record your […]

## Grades 9 to 11 Kissing Triangles

*By toni On 19 July, 2017 · Leave a Comment*

Find the total area of the two triangles by two different methods if ACD and BCE are straight lines .

What are the lengths PC and CQ?

The triangles are re-drawn keeping the total area the same and keeping the distances between the green parallel lines as 3 cm and BD = 4 cm.

## Grades 4 to 7 Tangram Pattern

*By toni On 3 June, 2017 · Leave a Comment*

Arrange the 7 tangram pieces to make the shape in the grey picture.

What do you notice about this shape?

Describe the shapes of the tangram pieces.

What is the same and what is different about the shapes of the tangram pieces?

Make a pattern of your own using all 7 pieces.

[…]

## Grades 7 to 9 Ratty

*By toni On 22 November, 2016 · Leave a Comment*

If you know the sizes of the angles marked with coloured dots in the diagram which angles can you find by calculation? Explain your reasoning.

If you also know that AB andĀ CD are parallel which angles can you find?

What extra information do you need to find all the numbered angles?

[…]

## Grades 8 to 12 Tri-Fold

*By toni On 13 September, 2016 · Leave a Comment*

Take any triangle and label it ABC with A as the largest angle. Fold the triangle along PQ, PS and QT where the points P and Q are the midpoints of AB and AC and PS and PT are perpendicular to BC.

What do you notice? Why does this happen? Will it […]

## Grades 7 to 9 Angle Sum

*By toni On 8 September, 2016 · Leave a Comment*

For any triangle you can construct a line through one of the verticesĀ parallel to the opposite edge.

Using what you know about angles and parallel lines prove that the angles of the triangle add up to 180 degrees.

## Grades 11 and 12 Bendy Quad

*By toni On 12 August, 2016 · Leave a Comment*

Four rods are hinged at their ends to form a convex quadrilateral with sides of length 3, 4, 5 and 6 (in that order). Investigate the different shapes that the quadrilateral can take if the polygon is always convex.

How do the angles change as the bendy quad changes shape?

Can any […]

## Grades 10 to 12 Trig Lengths

*By toni On 23 July, 2016 · Leave a Comment*

In the diagram the line OS is perpendicular to the lines OR and PQ.

The line RS is a tangent at P to the circle centre O and radius 1 unit.

Find the lengths OQ, PQ, PS, OS, OR and RP.

If OS and OR lie on the coordinate axes, what are the coordinates […]

## Grades 5 to 10 Find the Triangles

*By toni On 27 June, 2016 · 7 Comments*

## Grades 10 to 12 Three By One

*By toni On 1 June, 2016 · 2 Comments*

This rectangle measures three units by one unit.

The diagram shows three angles a, b and c.

How many ways can you prove that a + b = c?

What other interesting properties can you find?

When this activity was originally published on NRICH, two boys from Madras School in St Andrew’s, Scotland sent […]

### Login

### SUPPORT AIMSSEC