# 18 21 25 triangle

### Acute scalene triangle.

Sides: a = 18   b = 21   c = 25

Area: T = 185.731098826
Perimeter: p = 64
Semiperimeter: s = 32

Angle ∠ A = α = 45.03656507165° = 45°2'8″ = 0.78660203858 rad
Angle ∠ B = β = 55.63662785693° = 55°38'11″ = 0.97110362446 rad
Angle ∠ C = γ = 79.32880707142° = 79°19'41″ = 1.38545360232 rad

Height: ha = 20.63767764733
Height: hb = 17.68986655486
Height: hc = 14.85884790608

Median: ma = 21.26602916255
Median: mb = 19.0855334684
Median: mc = 15.04216089565

Inradius: r = 5.80440933831
Circumradius: R = 12.72200098494

Vertex coordinates: A[25; 0] B[0; 0] C[10.16; 14.85884790608]
Centroid: CG[11.72; 4.95328263536]
Coordinates of the circumscribed circle: U[12.5; 2.35655573795]
Coordinates of the inscribed circle: I[11; 5.80440933831]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 134.9644349284° = 134°57'52″ = 0.78660203858 rad
∠ B' = β' = 124.3643721431° = 124°21'49″ = 0.97110362446 rad
∠ C' = γ' = 100.6721929286° = 100°40'19″ = 1.38545360232 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.