# 11 16 21 triangle

### Obtuse scalene triangle.

Sides: a = 11   b = 16   c = 21

Area: T = 86.53332306111
Perimeter: p = 48
Semiperimeter: s = 24

Angle ∠ A = α = 31.00327191339° = 31°10″ = 0.5411099526 rad
Angle ∠ B = β = 48.52215991697° = 48°31'18″ = 0.84768616638 rad
Angle ∠ C = γ = 100.4765681696° = 100°28'32″ = 1.75436314638 rad

Height: ha = 15.73333146566
Height: hb = 10.81766538264
Height: hc = 8.24112600582

Median: ma = 17.84395627749
Median: mb = 14.73109198627
Median: mc = 8.84659030065

Inradius: r = 3.60655512755
Circumradius: R = 10.67879787773

Vertex coordinates: A[21; 0] B[0; 0] C[7.28657142857; 8.24112600582]
Centroid: CG[9.42985714286; 2.74770866861]
Coordinates of the circumscribed circle: U[10.5; -1.94114506868]
Coordinates of the inscribed circle: I[8; 3.60655512755]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 148.9977280866° = 148°59'50″ = 0.5411099526 rad
∠ B' = β' = 131.478840083° = 131°28'42″ = 0.84768616638 rad
∠ C' = γ' = 79.52443183036° = 79°31'28″ = 1.75436314638 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.