Shapes

Question 1

How do you calculate the total of interior angles within a regular shape

Answer 1

N (number)

(N-2)×180

Question 2

What is the area of a trapizium

Answer 2

1/2(a+b)h

Question 3

What is the area of a circle

Answer 3

πr^2

Question 4

What is the area of a quadrent

Answer 4

(πr^2)÷4

Question 5

What is the area of a sector

Answer 5

(πr^2) × (angle of sector ÷360)

Question 6

When given two sets of coordinates, the centre of the circle, and one on the edge how do you find the gradient of the tangent in the edge

Answer 6

Find the gradient of that line
That line will be perpendicular to the tangent
The gradient of perpendicular lines is -1/m

Question 7

How to find the shaded area of three equal overlapping circles

Answer 7

First find the area of a sector, this sector is drawn by joining two lines from the centre to the circumference. As an equilateral triangle is formed, you would do 60/360 × πr^2

The red area can be found = area of triangle - 1 segment (as the sides would cancel out 1)

The triangle area is found using sine rule

Area of a segment = area of the sector - area of the triangle

Then multiply by 2 to get both shaded areas

Question 8

What is the volume of a sphere

Answer 8

4/3×π×r^3

Question 9

What is the surface area of a sphere

Answer 9

4πr^2

Question 10

What is the volume of a cylinder

Answer 10

π×r^2×h

Question 11

What is the surface area of a cylinder

Answer 11

(2×π×r×h)+(2×π×r^2)

First equation is for the middle area (circumference × length)

Second is for the two bases (area of a circle)