GEOMETRY A line segment through a focus of an ellipse with endpoints on the ellipse and perpendicular to the major axis is called a latus rectum of the ellipse. Therefore, an ellipse has two latera recta. Knowing the length of the latera recta is helpful in sketching an ellipse because it yields other points on the curve (see figure). Show that the length of each latus rectum is

MATH 21 WEEK 1 NOTES Area of a Circle π is a constant that can, for the purposes of the SAT, be written as 3.14 (or 3.14159 r is the radius of the circle (any line drawn from the center point straight to the edge of the circle) Circumference of a Circle C=2πr or C=πd d is the diameter of the circle. It is a line that bisects the circle through the midpoint and touches two ends of the circle on opposite sides. It is twice the radius. Area of a Rectangle • l is the length of the rectangle • w is the width of the rectangle Area of a Triangle • b is the length of the base of triangle (the edge of one side) • h is the height of the triangle In a right triangle, the h