Trig can look really scary in 3D….but if you keep calm and simplify it by drawing it as 2D shapes you’ll be rewarded with an A*.
Example: ABCDEFGH is a cuboid with dimensions 8cm, 6cm and 5cm.
To do this sketch the base of the cuboid and draw the line AC. Now you can see to find AC you have a simple Pythagoras problem.
For this draw triangle ACG. So again you have Pythagoras.