Mathematic Knowledge

Today I presented a Mathematics Knowledge question about a circle.  I remind my students of the importance of knowing geometry formulas for all the shapes. Knowing the formulas for circumference of a circle and area of a circle are important circles to know.  Today’s question is:

If the radius of a circle is 15, what is the diameter?  Do you know how a radius compares to the length of a diameter?  I will present the answer tomorrow