Triangle Calculator: Solve Any Geometry Problem

Calculate angles, sides, and area with mathematical precision.

Whether you are cutting lumber for a roof pitch, helping with high school trigonometry, or calculating the square footage of a triangular garden plot, our Triangle Calculator provides instant results. Simply input any three known values (at least one side) to find the remaining measurements, the perimeter, and the area.

Types of Triangles & Formulas

On familyhealthcalc.com, we use several geometric principles to solve your inputs:

1. The Pythagorean Theorem

For a Right Triangle (where one angle is 90°), the relationship between sides is:

a² + b² = c²

2. Area Calculation (Heron’s Formula)

When you only know the three side lengths, we use Heron’s formula to find the area:

Area = √(s(s − a)(s − b)(s − c))

where s is the semi-perimeter: a + b + c 2

3. Law of Sines & Cosines

For Oblique Triangles (no right angle), we use these laws to solve for missing variables:

Law of Sines: a sin A = b sin B = c sin C

Law of Cosines: c² = a² + b² − 2ab cos C

Practical “Real World” Uses

• Home Improvement: Calculating the length of a banister (hypotenuse) given the height and width of a staircase.
• Navigation: Using triangulation to find the distance between three points on a map.
• Landscaping: Measuring the exact area of a corner lot for mulch or sod ordering.
• Art & Design: Ensuring symmetry in triangular patterns or woodworking joints.