Cubes and Cube Roots Arithmetic

Cubes and cube roots ( all measurements will be assumed to be in centimetres ) The volume of the cube shown is 5  5  5 which is 125 cm 3. What is the volume of this cube ? 5cm 3cm

Cubes and cube roots What are the volumes of the two cubes below ? 8cm 4cm

Cubes and cube roots Suppose now that you were told the volume of a cube and you were asked to find the length of the side of the cube. For example, the cube shown has a volume of 216cm 3, what is the length of the side of the cube? 

Cubes and cube roots Find the length of the sides of these cubes Volume =1000 Volume = 343

Cubes and cube roots You are going now to use a trial and error method to find the length of the side of the cube. In the diagrams below you will initially guess at the answer and then try to improve on your guess and get a better and better answer for the length of the side of the cube. Try to find the length of the sides of these cubes Volume = 200cm 3 Volume =75cm 3 Try to get your answers correct to 3 decimal places.

Cubes and cube roots The cube root button Look at your calculator and see if you can find the cube root symbol. It should look like this 3 . You will need to press the MATHS button first to see it if you are using a graphic calculator. This 3  is called the cube root button. Use it to find 3 25 3 45 3 105 3 80 3 120 3 500

Cubes and cube roots Your answers should look like those in the diagram shown. Look back at the answers you got for the sides of the cubes on the previous slide. Do you see how you might use the cube root button to help you find the side of a cube very easily.

Cubes and cube roots Use the cube root button on your calculator to find the lengths of the sides of the cubes shown. Volume = 640cm 3 Volume = 200cm 3 Volume = 400cm 3 Volume = 850cm 3