Step by step
The question
Question: construct triangle A B C with A B = 9 cm, B C = 7 cm and A C = 6 cm, using a ruler and compasses.
triangle ABC: AB = 9 cm, BC = 7 cm, AC = 6 cm
We only use a ruler for straight lines and a pair of compasses for arcs.
The arcs stay on the paper.
ruler: straight lines; compasses: arcs
1 Draw the base
With the ruler, draw A B, 9 cm long.
2 Arc from A
Open the compass to A C, 6 cm.
Put the point on A and draw an arc where C will be.
Careful!
Leave the arcs on the paper.
They show how the triangle was made.
Careful: do not rub out the arcs
3 Arc from B
Open the compass to B C, 7 cm.
From B, draw an arc.
The two arcs cross at C.
4 Join
With the ruler, join A to C and B to C.
5 Check
Let's check with the ruler: A C is 6 cm and B C is 7 cm, as asked.
So the triangle is right!
measure: AC = 6 cm, BC = 7 cm
Let's look back.
First: draw the base.
Then: arc from A.
Then: arc from B.
Then: join.
Last: check.
Answer
triangle ABC: AB = 9 cm, BC = 7 cm, AC = 6 cm