Physical quantities and measurement techniques — Determine

How do you find the resultant of two forces (or velocities) acting at right angles to each other?

Graphically: draw the two vectors to scale as two sides of a right-angled triangle, tip to tail, then draw and measure the third side (the resultant) with a ruler and protractor to find its magnitude and direction. By calculation: use Pythagoras' theorem, resultant = √(F1² + F2²), and trigonometry (tan θ = opposite/adjacent) to find the angle from a stated direction.