Idea 14of 24Builds onName a triangle by its angles
One triangle, two names
Can one triangle have two names at once?
Today you'll discover
- how to give a triangle both names
- which pairs of names go together
- which pair can never happen
Think firstAngles of 45°, 90° and 45°
It has two equal sides and angles of 45°, 90° and 45°. Which names fit?
Decide first, then press Next. Read the two name boxes on the right.
A triangle with two equal sides, ticked, and angles 45°, 90° and 45°. Two boxes then name it: isosceles by its sides and right by its angles. Then a triangle with sides 7, 3 and 5 cm named scalene and obtuse, and an equilateral triangle named equilateral and acute. The last step asks which pair of names can never be drawn.
See the whole ideathe big idea and the key word, in one place
The big idea
Every triangle has two names: one from its sides and one from its angles.
Name pairs that existRight isosceles: 45°, 90°, 45°. Obtuse scalene: 22°, 38°, 120°. Acute equilateral: 60°, 60°, 60°. Right scalene: sides 3, 4 and 5 cm.
Easy to get wrongSay both names when you classify. Isosceles alone says nothing about the angles; right alone says nothing about the sides.
Key word
- classify
- sort something into a group by what it is like, and give it that group's name
Ready to use it?
- Classify a triangle by its sides and by its angles.