# 2 4 5 triangle

### Obtuse scalene triangle.

Sides: a = 2   b = 4   c = 5

Area: T = 3.87996710384
Perimeter: p = 11
Semiperimeter: s = 5.5

Angle ∠ A = α = 22.33216450092° = 22°19'54″ = 0.39897607328 rad
Angle ∠ B = β = 49.45883981265° = 49°27'30″ = 0.86332118901 rad
Angle ∠ C = γ = 108.2109956864° = 108°12'36″ = 1.88986200307 rad

Height: ha = 3.87996710384
Height: hb = 1.98998355192
Height: hc = 1.52198684154

Median: ma = 4.41658804332
Median: mb = 3.24403703492
Median: mc = 1.93664916731

Inradius: r = 0.69108492797
Circumradius: R = 2.63218067798

Vertex coordinates: A[5; 0] B[0; 0] C[1.3; 1.52198684154]
Centroid: CG[2.1; 0.50766228051]
Coordinates of the circumscribed circle: U[2.5; -0.82224396187]
Coordinates of the inscribed circle: I[1.5; 0.69108492797]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 157.6688354991° = 157°40'6″ = 0.39897607328 rad
∠ B' = β' = 130.5421601874° = 130°32'30″ = 0.86332118901 rad
∠ C' = γ' = 71.79900431357° = 71°47'24″ = 1.88986200307 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.