# 20 21 25 triangle

### Acute scalene triangle.

Sides: a = 20   b = 21   c = 25

Area: T = 202.9388414303
Perimeter: p = 66
Semiperimeter: s = 33

Angle ∠ A = α = 50.63329726582° = 50°37'59″ = 0.8843712083 rad
Angle ∠ B = β = 54.26876240296° = 54°16'3″ = 0.94771487166 rad
Angle ∠ C = γ = 75.09994033122° = 75°5'58″ = 1.31107318541 rad

Height: ha = 20.29438414303
Height: hb = 19.32774680289
Height: hc = 16.23550731443

Median: ma = 20.80986520467
Median: mb = 20.05661711201
Median: mc = 16.2565768207

Inradius: r = 6.15496489183
Circumradius: R = 12.93549586623

Vertex coordinates: A[25; 0] B[0; 0] C[11.68; 16.23550731443]
Centroid: CG[12.22766666667; 5.41216910481]
Coordinates of the circumscribed circle: U[12.5; 3.32661322274]
Coordinates of the inscribed circle: I[12; 6.15496489183]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 129.3677027342° = 129°22'1″ = 0.8843712083 rad
∠ B' = β' = 125.732237597° = 125°43'57″ = 0.94771487166 rad
∠ C' = γ' = 104.9010596688° = 104°54'2″ = 1.31107318541 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.