unit 4

• a tangent is a line that touches a circle at a single point on the circumference
• tangency is the point on the circumference that the line touches
• a line that is tangent to a circle is perpendicular to a radius drawn to the point of tangency
• if a line is perpendicular to a chord and goes through the center than the line also bisects the chord
• If there are 2 non-parallel tangents to the same circle than, from the point of tangency to the point that they intersect, they are equal.
• the angle of rotation of an arc is the same as the interior angle
• the tsa of a cone is: πr^2+πrs
• the surface area of a sphere: 4πr^2
• the volume of a sphere: 4/3πr^3
• volume of a pyramid: 1/3Bh
• tsa of a cylinder: 2πr^2+2πrh
• the arc measure: Θ