# 4 17 18 triangle

### Obtuse scalene triangle.

Sides: a = 4   b = 17   c = 18

Area: T = 33.66765635312
Perimeter: p = 39
Semiperimeter: s = 19.5

Angle ∠ A = α = 12.71215526646° = 12°42'42″ = 0.2221858447 rad
Angle ∠ B = β = 69.25876200455° = 69°15'27″ = 1.20987735019 rad
Angle ∠ C = γ = 98.03108272899° = 98°1'51″ = 1.71109607047 rad

Height: ha = 16.83332817656
Height: hb = 3.96107721801
Height: hc = 3.74107292812

Median: ma = 17.39325271309
Median: mb = 9.88768599666
Median: mc = 8.45657672626

Inradius: r = 1.72664904375
Circumradius: R = 9.08991367548

Vertex coordinates: A[18; 0] B[0; 0] C[1.41766666667; 3.74107292812]
Centroid: CG[6.47222222222; 1.24769097604]
Coordinates of the circumscribed circle: U[9; -1.27698058702]
Coordinates of the inscribed circle: I[2.5; 1.72664904375]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 167.2888447335° = 167°17'18″ = 0.2221858447 rad
∠ B' = β' = 110.7422379954° = 110°44'33″ = 1.20987735019 rad
∠ C' = γ' = 81.96991727101° = 81°58'9″ = 1.71109607047 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.