- Arcs are proportional to the circumference based on the central angle: =
.
- Sectors are proportional to the area based on the central angle: = .
- If the central angle is given in radians, the measure of the arc is given by s = rθ.
◦ Rectangles and squares:
- The perimeter of a rectangle is the sum of the lengths of its sides.
- The area of a rectangle is length × width.
- A square is a rectangle whose four sides are all equal in length.
- Any polygon can be divided into triangles.
- The volume of a rectangular solid is length × width × height. The formulas to compute the
volumes of other three-dimensional figures are supplied in the instructions at the front of both
Math sections.
◦ When you encounter a geometry problem on the SAT, Ballpark the answer before trying to work it
out.
◦ You must be familiar with the size of certain common angles.
◦ Most SAT geometry diagrams are drawn to scale. Use your eyes before you use your pencil. Try to
eliminate impossible answers.
◦ When a diagram is not drawn to scale, redraw it.
◦ When no diagram is provided, make your own; when a provided diagram is incomplete, complete it.
◦ When information is missing from a diagram, Ballpark and Plug In.