Formulas to remember

Question 1

What is the formula for the area of a trapezium?

Answer 1

1/2 (a + b) x h

Question 2

What is the cross section of a prism?

Answer 2

The cross section is the shape made by cutting straight across an object. (e.g. the cross section of a triangular prism looks like a triangle)

Question 3

What is the formula for the volume of a prism?

Answer 3

length x width x height

Question 4

If you have a right-angled triangle, what do you use to work out the missing sides or angles?

Answer 4

Trigononemtry

Question 5

If you are using the adjacent and hypotenuse, which trigonometric ratio do you use?

Answer 5

Cos

Question 6

If you are using the opposite and hypotenuse, which trigonometric ratio do you use?

Answer 6

Sin

Question 7

If you are using the opposite and adjacent, which trigonometric ratio do you use?

Answer 7

Tan

Question 8

What is the formula to find the area of any triangle?

Answer 8

1/2 ab sin c

Question 9

What is the sine rule?

Answer 9

SinA/a = SinB/b = SinC/c
or
a/SinA = b/SinB = c/SinC

Question 10

What is the cosine rule?

Answer 10

a² = b² + c² - 2bc cos A

Question 11

You use the sine rule when …

Answer 11

• it is a not a right-angled triangle
• we are given two sides and an angle opposite to one of the two sides
• or one side and any two angles

Question 12

You use the cosine rule when …

Answer 12

• it is not a right-angled triangle
• two sides and an angle are given
• or three sides are given