# 11 19 21 triangle

### Acute scalene triangle.

Sides: a = 11   b = 19   c = 21

Area: T = 103.9966093677
Perimeter: p = 51
Semiperimeter: s = 25.5

Angle ∠ A = α = 31.41883975029° = 31°25'6″ = 0.54883544821 rad
Angle ∠ B = β = 64.21105741313° = 64°12'38″ = 1.12106859332 rad
Angle ∠ C = γ = 84.37110283658° = 84°22'16″ = 1.47325522383 rad

Height: ha = 18.90883806685
Height: hb = 10.94769572291
Height: hc = 9.9044389874

Median: ma = 19.2554869514
Median: mb = 13.81112273169
Median: mc = 11.4354596626

Inradius: r = 4.07882781834
Circumradius: R = 10.55108770686

Vertex coordinates: A[21; 0] B[0; 0] C[4.78657142857; 9.9044389874]
Centroid: CG[8.59552380952; 3.30114632913]
Coordinates of the circumscribed circle: U[10.5; 1.03548946407]
Coordinates of the inscribed circle: I[6.5; 4.07882781834]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 148.5821602497° = 148°34'54″ = 0.54883544821 rad
∠ B' = β' = 115.7899425869° = 115°47'22″ = 1.12106859332 rad
∠ C' = γ' = 95.62989716342° = 95°37'44″ = 1.47325522383 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.