# 2 9 10 triangle

### Obtuse scalene triangle.

Sides: a = 2   b = 9   c = 10

Area: T = 8.1821534086
Perimeter: p = 21
Semiperimeter: s = 10.5

Angle ∠ A = α = 10.47553138432° = 10°28'31″ = 0.18328287167 rad
Angle ∠ B = β = 54.99003678046° = 54°54'1″ = 0.95881921787 rad
Angle ∠ C = γ = 114.6244318352° = 114°37'28″ = 2.00105717581 rad

Height: ha = 8.1821534086
Height: hb = 1.81881186858
Height: hc = 1.63663068172

Median: ma = 9.46604439642
Median: mb = 5.63547138348
Median: mc = 4.18333001327

Inradius: r = 0.77991937225
Circumradius: R = 5.55001909822

Vertex coordinates: A[10; 0] B[0; 0] C[1.15; 1.63663068172]
Centroid: CG[3.71766666667; 0.54554356057]
Coordinates of the circumscribed circle: U[5; -2.29217462426]
Coordinates of the inscribed circle: I[1.5; 0.77991937225]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 169.5254686157° = 169°31'29″ = 0.18328287167 rad
∠ B' = β' = 125.1099632195° = 125°5'59″ = 0.95881921787 rad
∠ C' = γ' = 65.37656816478° = 65°22'32″ = 2.00105717581 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.