# 17 25 28 triangle

### Acute scalene triangle.

Sides: a = 17   b = 25   c = 28

Area: T = 210
Perimeter: p = 70
Semiperimeter: s = 35

Angle ∠ A = α = 36.87698976458° = 36°52'12″ = 0.64435011088 rad
Angle ∠ B = β = 61.92875130641° = 61°55'39″ = 1.08108390005 rad
Angle ∠ C = γ = 81.203258929° = 81°12'9″ = 1.41772525443 rad

Height: ha = 24.70658823529
Height: hb = 16.8
Height: hc = 15

Median: ma = 25.14545819214
Median: mb = 19.5
Median: mc = 16.15554944214

Inradius: r = 6
Circumradius: R = 14.16766666667

Vertex coordinates: A[28; 0] B[0; 0] C[8; 15]
Centroid: CG[12; 5]
Coordinates of the circumscribed circle: U[14; 2.16766666667]
Coordinates of the inscribed circle: I[10; 6]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 143.1330102354° = 143°7'48″ = 0.64435011088 rad
∠ B' = β' = 118.0722486936° = 118°4'21″ = 1.08108390005 rad
∠ C' = γ' = 98.797741071° = 98°47'51″ = 1.41772525443 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    