Assess Yourself

Try again! An obtuse triangle needs to have an obtuse angle.

Try again. An equilateral triangle has sides that are all the same length.

Correct. This triangle has three acute angles.

Try again. A right triangle needs to have a 90-degree angle.

Try again. An isosceles triangle has two equal sides.

Try again. A right triangle does not have three equal sides.

Try again. A scalene triangle has no equal sides.

Correct! A triangle with three equal sides is an equilateral triangle. 

Try again. An acute angle has all acute angles.

ry again. An obtuse triangle has one obtuse and two acute angles.

Correct. A right triangle has a right angle.

Try again. A right triangle has a 90-degree angle. 

Try again. An acute angle has all acute angles.

Correct. There is an obtuse angle in the triangle.

No. An equilateral triangle has all three sides the same length.

Try again. An isosceles triangle has two sides that are the same length.

Try again. An equilateral triangle has three equal sides.

Correct. This triangle has one right angle.

Try again. An acute triangle has three acute angles.

Try again. An isosceles triangle has two equal sides.

Try again. A right triangle has a right angle. 

Incorrect.  An equilateral triangle has three equal sides.

Yes. A scalene triangle has no equal sides.

Correct. These sails have 90-degree angles.

Try again. A right triangle has a square corner.

Try again. A right triangle has a 90-degree angle.

Try again. An equilateral triangle is a triangle with three sides that are equal in length.

Try again. An isosceles triangle has two equal sides.

Try again. An acute triangle has three acute angles.

Correct. A scalene triangle is a triangle with no sides equal in length.

Try again. An acute triangle has more than one acute angle.

Try again. An acute triangle has more than two acute angles.

Correct. An acute triangle has three acute angles.

Try again. An acute triangle has acute angles.

Try again. All triangles have three sides and three angles.

Close! There's a missing answer. All triangles have three sides and three angles.

Correct! You can identify triangles by their angles. The length of the sides in relationship to one another helps identify triangles.