# 25 26 28 triangle

### Acute scalene triangle.

Sides: a = 25   b = 26   c = 28

Area: T = 298.1943624177
Perimeter: p = 79
Semiperimeter: s = 39.5

Angle ∠ A = α = 55.00661147587° = 55°22″ = 0.96600378113 rad
Angle ∠ B = β = 58.42878777762° = 58°25'40″ = 1.02197588421 rad
Angle ∠ C = γ = 66.5666007465° = 66°33'58″ = 1.16217960002 rad

Height: ha = 23.85554899342
Height: hb = 22.93879710906
Height: hc = 21.32995445841

Median: ma = 23.9533079134
Median: mb = 23.14108729308
Median: mc = 21.31990056053

Inradius: r = 7.54992056754
Circumradius: R = 15.25985422058

Vertex coordinates: A[28; 0] B[0; 0] C[13.08992857143; 21.32995445841]
Centroid: CG[13.69664285714; 7.10998481947]
Coordinates of the circumscribed circle: U[14; 6.06882048618]
Coordinates of the inscribed circle: I[13.5; 7.54992056754]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 124.9943885241° = 124°59'38″ = 0.96600378113 rad
∠ B' = β' = 121.5722122224° = 121°34'20″ = 1.02197588421 rad
∠ C' = γ' = 113.4343992535° = 113°26'2″ = 1.16217960002 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    