# 7 16 21 triangle

### Obtuse scalene triangle.

Sides: a = 7   b = 16   c = 21

Area: T = 44.49771909226
Perimeter: p = 44
Semiperimeter: s = 22

Angle ∠ A = α = 15.35988855808° = 15°21'32″ = 0.26880631228 rad
Angle ∠ B = β = 37.25879160013° = 37°15'29″ = 0.65502733067 rad
Angle ∠ C = γ = 127.3833198418° = 127°23' = 2.22332562241 rad

Height: ha = 12.71334831207
Height: hb = 5.56221488653
Height: hc = 4.23878277069

Median: ma = 18.33771208209
Median: mb = 13.45436240471
Median: mc = 6.5

Inradius: r = 2.02325995874
Circumradius: R = 13.21443173043

Vertex coordinates: A[21; 0] B[0; 0] C[5.57114285714; 4.23878277069]
Centroid: CG[8.85771428571; 1.41326092356]
Coordinates of the circumscribed circle: U[10.5; -8.02329783633]
Coordinates of the inscribed circle: I[6; 2.02325995874]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 164.6411114419° = 164°38'28″ = 0.26880631228 rad
∠ B' = β' = 142.7422083999° = 142°44'31″ = 0.65502733067 rad
∠ C' = γ' = 52.61768015821° = 52°37' = 2.22332562241 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.