Triangle Calculator — Sides Angles Area

Triangle Diagram

Triangle Solver Calculator

Enter at least 3 known values (at least one must be a side). Leave unknown fields blank.

Calculate Triangle

📹 Video Walkthrough — How to Use This Calculator

Mathematical Equations

Law of Sines

Use the formula below to calculate sides and angles using the Law of Sines.

a/sin(A) = b/sin(B) = c/sin(C)

Law of Cosines

Use the formula below to calculate an unknown side when two sides and the included angle are known.

c² = a² + b² - 2ab·cos(C)
b² = a² + c² - 2ac·cos(B)
a² = b² + c² - 2bc·cos(A)

Heron's Formula for Area

Use the formula below to calculate triangle area from three known sides.

s = (a + b + c)/2
Area = √[s(s-a)(s-b)(s-c)]

Alternative Area Formulas

Use the formula below to calculate triangle area when two sides and the included angle are known.

Area = ½ab·sin(C)
Area = ½ac·sin(B)
Area = ½bc·sin(A)

Triangle Theory & Engineering Applications

The triangle solver calculator all sides angles represents one of the most fundamental tools in engineering mathematics. Triangular analysis forms the backbone of structural mechanics, surveying, navigation, and countless mechanical design applications where precise geometric relationships must be determined.

Fundamental Triangle Properties

Every triangle possesses six basic elements: three sides (a, b, c) and three angles (A, B, C). The sum of interior angles always equals 180 degrees, a property that enables us to solve for unknown values when sufficient information is provided. This triangle solver calculator all sides angles utilizes this fundamental principle combined with trigonometric relationships.

The law of sines establishes proportional relationships between sides and their opposite angles, making it invaluable for solving triangles when two angles and one side are known (ASA or AAS cases), or when two sides and a non-included angle are known (SSA case, though this may yield ambiguous solutions).

The law of cosines extends the Pythagorean theorem to all triangles, not just right triangles. It's particularly useful for solving triangles when three sides are known (SSS case) or when two sides and the included angle are known (SAS case).

Engineering Applications

In mechanical engineering, triangular calculations are essential for truss analysis, where structural members form triangular configurations to distribute loads efficiently. Engineers must calculate member forces, joint reactions, and deflections using precise triangular geometry.

For automation systems utilizing FIRGELLI linear actuators, triangular analysis becomes critical when actuators are mounted at angles or work within linkage mechanisms. The force vectors, mounting angles, and effective stroke lengths all require precise triangular calculations to ensure proper system operation.

Surveying and GPS applications rely heavily on triangulation techniques, where unknown positions are determined by measuring angles and distances to known reference points. The triangle solver calculator all sides angles enables surveyors to establish precise coordinates and elevations across terrain.

Manufacturing and Machining

In manufacturing, triangular calculations determine cutting angles, fixture positions, and part orientations. CNC programming frequently requires conversion between coordinate systems and angular measurements, where our triangle solver calculator proves invaluable.

Quality control processes use coordinate measuring machines (CMMs) that establish part dimensions through triangular measurements. Geometric tolerancing and inspection procedures rely on precise triangular analysis to verify part conformance to specifications.

Robotics and Automation

Robotic arm kinematics involves complex triangular calculations to determine end-effector positions and joint angles. Forward and inverse kinematics solutions require solving multiple triangular relationships simultaneously.

Automated guided vehicles (AGVs) use triangulation for navigation and positioning. Laser guidance systems, vision systems, and magnetic guidance all incorporate triangular analysis for precise path following and obstacle avoidance.

Worked Example

Problem: Linear Actuator Mounting Analysis

An engineer needs to mount a linear actuator to lift a platform. The actuator mounting point is 12 inches from the pivot, the platform connection point is 18 inches from the pivot, and the actuator must provide a 45-degree lift angle when fully extended.

Solution Steps:

Step 1: Use the Law of Cosines to find side a (actuator length)

a² = b² + c² - 2bc·cos(C)
a² = 18² + 12² - 2(18)(12)·cos(45°)
a² = 324 + 144 - 432 × 0.7071
a² = 468 - 305.47
a² = 162.53
a = 12.75 inches

Step 2: Use the Law of Sines to find angle A (actuator angle)

sin(A)/a = sin(C)/c
sin(A) = a × sin(C)/c
sin(A) = 12.75 × sin(45°)/12
sin(A) = 12.75 × 0.7071/12
sin(A) = 0.7513
A = 48.76°

Step 3: Calculate angle B

B = 180° - A - C
B = 180° - 48.76° - 45°
B = 86.24°

Step 4: Calculate triangle area (mechanism sweep area)

Area = ½bc·sin(A)
Area = ½ × 18 × 12 × sin(48.76°)
Area = 108 × 0.7513
Area = 81.14 square inches

Frequently Asked Questions

About the Author

Robbie Dickson

Chief Engineer & Founder, FIRGELLI Automations

Robbie Dickson brings over two decades of engineering expertise to FIRGELLI Automations. With a distinguished career at Rolls-Royce, BMW, and Ford, he has deep expertise in mechanical systems, actuator technology, and precision engineering.