Circles

Question 1

Area of a circle?

Answer 1

π*radius^2

Question 2

Circumference of a circle

Answer 2

π*diametre or 2πr

Question 3

Perimeter of a sector?

Answer 3

Archlength+diameter OR (depending on what information u have), (πdiameterfraction of circle(angle/360°))+diameter

Question 4

What is a sector?

Answer 4

A section of a circle
(It’s kind of like cutting a piece of cake)

Question 5

Area of of a sector

Answer 5

Fraction of circle (angle/360°)πradius of circle

Question 6

How to find the archlength?

Answer 6

Fraction of circle (angle/36°)πdiameter

Question 7

What is the equation for the volume of a cylinder?

Answer 7

πradius^2height
It’s basically the area of the circle*height

Question 8

What is the equation for the surface area of a cylinder?

Answer 8

(πdiameterheight)+(2πradius^2)
It’s basically the surface area of the rectangle+the 2 circles’s area

Question 9

What is the equation for the volume of a sphere?

Answer 9

(4π*r^3) / 3

Question 10

What is the equation for the surface area of a sphere?

Answer 10

4π*r^2

Question 11

What is the equation for the volume of a cone?

Answer 11

1/3 πr^2*h

Question 12

What is the equation for the surface area of a cone?

Answer 12

(πrl)+(π*r^2)
The l is the slanted height and NOT the perpendicular height

Question 13

How to find the area of a frustum? (When u cut off the top bit of a cone)

Answer 13

1/3 πh (R^2 + R*r + r^2)

The capital R is the radius of the base of the frustum
The little r is the radius of the top bit
h is the perpendicular height of the frustum