Warm Up May 14th Find the area and circumference of a circle with a diameter of 9 in. Find the area of a circle is the circumference is 41 ft. Find the perimeter and area of the shape. 6 yd 4 yd

Homework Questions??

Equations of Circles Definition: A circle is the set of all points in a plane at a distance “ r ” (radius) from a given point called the center. If the circle has its center at the origin, the equation is of the form x2 + y2 = r2

Radius of a Circle x2 + y2 = 25 is a circle with a center at ( , ) and a radius of ______. To change the size of the circle, just change r. Write the equation of a circle with a center at the origin that has a radius of 7.

Center of a Circle If we want to change the center, we have to change the equation. The standard form for the equation of a circle not centered at the origin is (x – h)2 + (y – k)2 = r2 where (h, k) is the center and r is the radius of the circle.

Equations of a Circle Write an equation of the circle in standard form. Center Radius Equation (2, 3) 5 (6, -2) -13 (-4, -9) 2.5

Equations of a Circle BE CAREFUL! Make sure you read/understand the information given to you. Write an equation of a circle with diameter of 24, centered at (4, -3).

Graphing a Circle Graph a circle with a center at (4, 2) and a radius of 3

Graphing a Circle (x + 2)2 + (y – 3)2 = 16 Graph this circle after finding its radius and center: (x + 2)2 + (y – 3)2 = 16 Center: __________ Radius: __________

Equations from a Graph Write the equation for the circle shown below. Find the circumference & area.

Equations from a Graph Write the equation for the circle shown below. Find the circumference & area.

Using Distance & Midpoint w/ Circles Recall the distance between two points can be found using the distance formula: Write the equation of a circle that passes through (3, -4) and has a center at the origin.

Using Distance to Find Radius Write the equation of a circle that passes through (1, 9) and has a center at (6, 7).

Using Distance to Find Radius Write the equation of a circle that passes through (-6, 20) and has a center at (2, 5).

Using Midpoint to Find Center Write the equation of a circle with a diameter that goes from (0, 0) to (10, 24) Center? Midpoint Formula Radius? Distance Formula Equation: ___________________