You may also like

problem icon

Building Tetrahedra

Can you make a tetrahedron whose faces all have the same perimeter?

problem icon

Ladder and Cube

A 1 metre cube has one face on the ground and one face against a wall. A 4 metre ladder leans against the wall and just touches the cube. How high is the top of the ladder above the ground?

problem icon

Areas and Ratios

What is the area of the quadrilateral APOQ? Working on the building blocks will give you some insights that may help you to work it out.

Circle in a Semicircle

Stage: 4 Short Challenge Level: Challenge Level:1

Ans: ½

Let the radius of the circle be r. This implies that the radius of the semicircle is 2r. The area of the semi circle is $1/2 \times \pi \times(2r)^2$, which is twice the area of the small circle.

This problem is taken from the UKMT Mathematical Challenges.