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Trigonometric Ratios of Acute Angles Calculator

Online right-triangle trig ratios calculator. Enter the two legs to get the hypotenuse and sin, cos, tan of angle A—ideal for trigonometry basics.

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sin=opp/hyp, cos=adj/hyp, tan=opp/adj
对边斜边A
Leg across from A
Leg next to A

📖 Tutorial | Trig Ratios

1. Definition
Given the two legs, find the hypotenuse and the three ratios for acute A.
2. Formula & Notation
a, bOpposite and adjacent to A
cHypotenuse √(a²+b²)
3. Properties & Laws
  • sin=a/c, cos=b/c, tan=a/b;
  • c=√(a²+b²);
  • sin and cos in 0–1;
  • sin²A+cos²A=1.
4. Steps
  1. Enter legs a and b;
  2. Click "Calculate";
  3. Or click "Load Example".
5. Worked Examples
Example: a=3, b=4.
Solution: c=5, sin0.6, cos0.8, tan0.75.
6. Common Pitfalls
Separate opposite and adjacent;
Hypotenuse via Pythagoras;
tan denominator is adjacent.

❓ FAQ | Trig Ratios

Three ratios?
sin, cos, tan.
Legs 3,4?
c=5; sin0.6, cos0.8, tan0.75.
Hypotenuse?
√(a²+b²).
Applies to?
Acute angles in right triangles.
tan?
opposite/adjacent.
sin²+cos²?
1.