Area and volume

Area and volume questions look simple until two formulas blur together. This topic takes the shapes students mix up most and pulls them apart. You start with the area of a triangle, where the height must be perpendicular to the base, not the slanted side. Next is the circle, where area uses the radius squared and circumference does not, and where using the diameter in place of the radius quietly doubles or quadruples an answer. Arc length comes next: it is just a fraction of the circumference, set by the angle out of 360 degrees. The topic ends with the volume of a cylinder, a circle's area stacked up through the height. Across all of these, units give you a free check. Area should come out in square units and volume in cubic units, so if your units look wrong, your formula probably is too. Each page walks through one mistake, a guided example and three practice questions to try on your own.