# 17 19 21 triangle

### Acute scalene triangle.

Sides: a = 17   b = 19   c = 21

Area: T = 152.814422545
Perimeter: p = 57
Semiperimeter: s = 28.5

Angle ∠ A = α = 49.99547991151° = 49°59'41″ = 0.87325738534 rad
Angle ∠ B = β = 58.88217045154° = 58°52'54″ = 1.0287679613 rad
Angle ∠ C = γ = 71.12334963694° = 71°7'25″ = 1.24113391872 rad

Height: ha = 17.97881441706
Height: hb = 16.08657079421
Height: hc = 14.55437357572

Median: ma = 18.13114643645
Median: mb = 16.57655844543
Median: mc = 14.65443508898

Inradius: r = 5.36219026474
Circumradius: R = 11.09768072181

Vertex coordinates: A[21; 0] B[0; 0] C[8.78657142857; 14.55437357572]
Centroid: CG[9.92985714286; 4.85112452524]
Coordinates of the circumscribed circle: U[10.5; 3.59901435117]
Coordinates of the inscribed circle: I[9.5; 5.36219026474]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 130.0055200885° = 130°19″ = 0.87325738534 rad
∠ B' = β' = 121.1188295485° = 121°7'6″ = 1.0287679613 rad
∠ C' = γ' = 108.8776503631° = 108°52'35″ = 1.24113391872 rad

# How did we calculate this triangle?

Now we know the lengths of all three sides of the triangle and the triangle is uniquely determined. Next we calculate another its characteristics - same procedure as calculation of the triangle from the known three sides SSS. ### 1. The triangle circumference is the sum of the lengths of its three sides ### 2. Semiperimeter of the triangle ### 3. The triangle area using Heron's formula ### 4. Calculate the heights of the triangle from its area. ### 5. Calculation of the inner angles of the triangle using a Law of Cosines ### 6. Inradius ### 7. Circumradius ### 8. Calculation of medians #### Look also our friend's collection of math examples and problems:

See more informations about triangles or more information about solving triangles.