What is the name of the blue part of this circle?

Any line that connects the center of a circle to the edge is a radius.

What is the name of the green part of this circle?

A line that connects one side of the circle to the other AND goes right through the center is called the *diameter* .

Maybe it would help to remember that if you get cut exactly in half, you die...*die-ameter.*

What is the name of the purple part of this circle?

The outside of the circle is the circumference. It's basically the perimeter of a circle.

Whenever you're asked about how far a revolution goes, it's asking about the circumference.

How are radius and diameter related?

The radius is the distance from the center of the circle to edge, and the diameter is the distance from one edge all the way to the other (going through the middle). So it's just two radii put together.

2 x radius = diameter

How can you tell if a triangle is an isosceles triangle?

A triangle is called isosceles when two sides are the exact same length. (This also means that two angles are the exact same size.)

What happens if you cut an isosceles triangle down the middle?

Well, if you cut in between the two equal sides, you make two right-angle triangles that are exactly the same.

(This is ONLY true for isosceles triangles.)

What type of triangle is this?

Isosceles triangle

What type of triangle is this?

Right (or right-angled) triangle.

What type of triangle is this?

Equilateral triangle.

All of the sides and all of the angles are exactly the same.

What type of triangle is this?

Scalene triangle

What shape is this?

A square. You can tell it's a square because all 4 sides are the same size and all of the corners are 90°.

What shape is this?

A rectangle. All of the corners of a rectangle are 90° and the opposite sides are the same size.

What shape is this?

A rhombus. Like a square, all of the sides are exactly the same size. UNLIKE a square, the angles are not all 90°. Opposite angles are the same, though.

What shape is this?

This shape has two names. Sometimes it's called a trapezium and sometimes a trapezoid.

Two of the sides are parallel. None of the sides have to be the same length and none of the angles have to be the same.

What shape is this?

This is a kite.

There are two short sides that are the same size and two long sides that are the same size.

Opposite angles are equivalent.

What shape is this?

This is a parallelogram. You can tell because the two sets of opposite sides are parallel, hence *parallel*ogram.

There are two short sides that are the same size and two long sides that are the same size.

Opposite angles are equivalent.

What shape is this?

This is a cylinder. It basically looks like a tin can. The top and bottom are circles of the same size.

What shape is this?

This is a sphere.

If you were to cut it in half the cut part would always look like a perfect circle.

The radius of a sphere goes from the exact middle to any edge.

What shape is this?

This is a cone, which is no surprise 'cause it looks like an ice-cream cone.

The radius of a cone is the radius of the circle at the bottom.

What shape is this?

This is a cone, which is no surprise 'cause it looks like an ice-cream cone.

The radius of a cone is the radius of the circle at the bottom.