Could someone please explain/help me to do this using Pythagoras theorem?

Step-by-step explanation:

→ First understand what Pythagoras theorem is

Pythagoras is a theorem used to find the hypotenuse (the side opposite to the right-angle) of a triangle. We would need the base lengths as well the height in order to use Pythagoras.

→ State the formula and identify the letters

a² + b² = c² ⇒ where 'a' is 380cm, 'b' is 290cm and 'c' is what we are trying to work out

→ Substitute in the values into the formula

380² + 290² = c²

⇒ Simplify

144400 + 84100 = c²

⇒ Collect the numbers together

228500 = c²

⇒ Square root both sides to find 'c'

478.0167361 = c

→ The length of the diagonal is 478.02