# 3 5 7 triangle

### Obtuse scalene triangle.

Sides: a = 3   b = 5   c = 7

Area: T = 6.49551905284
Perimeter: p = 15
Semiperimeter: s = 7.5

Angle ∠ A = α = 21.78767892983° = 21°47'12″ = 0.38802512067 rad
Angle ∠ B = β = 38.21332107017° = 38°12'48″ = 0.66769463445 rad
Angle ∠ C = γ = 120° = 2.09443951024 rad

Height: ha = 4.33301270189
Height: hb = 2.59880762114
Height: hc = 1.85657687224

Median: ma = 5.89549130613
Median: mb = 4.77696960071
Median: mc = 2.17994494718

Inradius: r = 0.86660254038
Circumradius: R = 4.04114518843

Vertex coordinates: A[7; 0] B[0; 0] C[2.35771428571; 1.85657687224]
Centroid: CG[3.1199047619; 0.61985895741]
Coordinates of the circumscribed circle: U[3.5; -2.02107259422]
Coordinates of the inscribed circle: I[2.5; 0.86660254038]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 158.2133210702° = 158°12'48″ = 0.38802512067 rad
∠ B' = β' = 141.7876789298° = 141°47'12″ = 0.66769463445 rad
∠ C' = γ' = 60° = 2.09443951024 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.