# 9 18 26 triangle

### Obtuse scalene triangle.

Sides: a = 9   b = 18   c = 26

Area: T = 44.39552418622
Perimeter: p = 53
Semiperimeter: s = 26.5

Angle ∠ A = α = 10.93766341702° = 10°56'12″ = 0.19108802754 rad
Angle ∠ B = β = 22.29994025333° = 22°17'58″ = 0.38991979954 rad
Angle ∠ C = γ = 146.7643963296° = 146°45'50″ = 2.56215143828 rad

Height: ha = 9.86656093027
Height: hb = 4.93328046514
Height: hc = 3.41550186048

Median: ma = 21.90331961138
Median: mb = 17.24881883107
Median: mc = 5.78879184514

Inradius: r = 1.67552921457
Circumradius: R = 23.71987580432

Vertex coordinates: A[26; 0] B[0; 0] C[8.32769230769; 3.41550186048]
Centroid: CG[11.44223076923; 1.13883395349]
Coordinates of the circumscribed circle: U[13; -19.8398837746]
Coordinates of the inscribed circle: I[8.5; 1.67552921457]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 169.063336583° = 169°3'48″ = 0.19108802754 rad
∠ B' = β' = 157.7010597467° = 157°42'2″ = 0.38991979954 rad
∠ C' = γ' = 33.23660367035° = 33°14'10″ = 2.56215143828 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.