Math Playground
Algebra

Trigonometry

sin, cos, tan and the right-triangle ratios behind every angle.

Trigonometry connects angles to side ratios in right triangles — and powers everything from architecture to GPS.

Drag around the circle
(0.866, 0.5)30°
θ = 30° = π/6
quadrant I
sin θ = y = 0.5
cos θ = x = 0.866
tan θ = sin/cos = 0.577
The three ratios (right triangle)

'Opp' and 'adj' are taken relative to the angle θ.

Your turn

A ramp rises 1 m over a 4 m horizontal run. What's the angle of incline?

Trig turns 'I can't reach it' into 'I can measure it': the height of a mountain, the distance to a star, the position from GPS satellites — all from angles and ratios.

Three ratios

  • sin θ = opposite / hypotenuse
  • cos θ = adjacent / hypotenuse
  • tan θ = opposite / adjacent