All Equations

Question 1

What is the cosine rule?

Answer 1

a2 = b2 + c2 - (2bc cos A)

re arrange to find other values e.g
Cos A = (b2 + c2 - a2)/2bc

Question 2

When do we use the cosine rule?

Answer 2

When we have been given:

• all three sides
• two sides and an angle

And want to find:
- an angle
-a side
from a non right angled triangle

Question 3

What is the Sine rule?

Answer 3

a/Sine A = b/Sin B = c/Sin C
re arrange to find e.g.
a = b/sin B x sine A

Question 4

When do we use the Sine rule?

Answer 4

When we are given either:
-Two sides and an angle opposite to one of the two sides
-One side and any two angles
To find either:
-a side
-an angle

Question 5

What is the formula to find the area of a non right angled triangle?

Answer 5

1/2 x ab x sin C

C is the angle in between sides a and b
a and b are two lengths either side of c

Question 6

What is the quadratic equation formula?

Answer 6

-b +/- √(b2 - 4ac) / 2a

Question 7

What is Pythagoras theorem?

Answer 7

a2 = b2 + c2

Question 8

How do you work out an angle when you are given two sides from a right angled triangle?

Answer 8

sOh cAh tOa

sin (x) =o/h 
Cos (x) =  a/h
Tan (x) = o/a
e.g.
x = -tan(o/h)

Question 9

What is the formula for the circumference of a circle?

Answer 9

2 x π x r

Question 10

What is the formula for the area of a circle?

Answer 10

π x r2

Question 11

What is the formula for the surface area of a hemisphere?

semi sphere

Answer 11

2 x pi x r2

Question 12

What is the formula for the volume of a sphere?

Answer 12

4/3 x (pi x r3)

Question 13

How do you find a fraction of number?

Answer 13

Divide by the bottom times by the top

by the bottom of the fraction and the top of the fraction

Question 14

What is the formula for volume of a cylinder?

Answer 14

pi x r2 x h

Question 15

What is the general equation of a circle?

Answer 15

(x - a)2 + (y - b)2 = r2