# 15 20 25 triangle

### Right scalene Pythagorean triangle.

Sides: a = 15   b = 20   c = 25

Area: T = 150
Perimeter: p = 60
Semiperimeter: s = 30

Angle ∠ A = α = 36.87698976458° = 36°52'12″ = 0.64435011088 rad
Angle ∠ B = β = 53.13301023542° = 53°7'48″ = 0.9277295218 rad
Angle ∠ C = γ = 90° = 1.57107963268 rad

Height: ha = 20
Height: hb = 15
Height: hc = 12

Median: ma = 21.36600093633
Median: mb = 18.02877563773
Median: mc = 12.5

Inradius: r = 5
Circumradius: R = 12.5

Vertex coordinates: A[25; 0] B[0; 0] C[9; 12]
Centroid: CG[11.33333333333; 4]
Coordinates of the circumscribed circle: U[12.5; 0]
Coordinates of the inscribed circle: I[10; 5]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 143.1330102354° = 143°7'48″ = 0.64435011088 rad
∠ B' = β' = 126.8769897646° = 126°52'12″ = 0.9277295218 rad
∠ C' = γ' = 90° = 1.57107963268 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    