SAT Math / High Yield Lessons
Read a circle’s center and radius from its equation, complete the square when the equation comes multiplied out, and find a polynomial’s x-intercepts from its factors.
A circle with center (1, negative 1) and radius 5 is drawn with a right triangle from its center to the point (4, 3): 3 right, 4 up, and 3 squared plus 4 squared equals 25, the radius squared. Next, a question asks what a circle's radius will do if r squared goes from 4 to 9, and the prediction grow from 4 to 9 is picked. Dragging the r squared slider to 9 grows the radius from 2 to 3, so that prediction is marked wrong and grow from 2 to 3 is marked right. Then the polynomial y equals one half (x plus 3)(x minus 1)(x minus 4) is drawn, crossing the x-axis at negative 3, 1, and 4. Finally, answer what the radius of (x plus 1) squared plus (y minus 2) squared equals 36 is, using the buttons after the picture.
