What is the Law of Cosines?

Note:

Keywords:

formula
law of cosines
cosine
triangle
sas
sss

Background Tutorials

Draw points, lines, line segments, rays, angles (right, acute, obtuse), and perpendicular and parallel lines. Identify these in two-dimensional figures.
- What are the Endpoints of a Line Segment?
  
  A math term can really tell you a lot about the thing it's describing. Take the term 'endpoints'. The endpoints of a line segment are just the 'points' located at the 'ends' of the line segment! That's an informative name! Watch this tutorial to learn about endpoints of a line segment.
- What is an Angle?
  
  Angles are a fundamental building block for creating all sorts of shapes! In this tutorial, learn about how an angle is formed, how to name an angle, and how an angle is measured. Take a look!
Classify two-dimensional figures based on the presence or absence of parallel or perpendicular lines, or the presence or absence of angles of a specified size. Recognize right triangles as a category, and identify right triangles.
- What are Acute, Obtuse, and Right Triangles?
  
  Did you know that there are different kinds of triangles? Knowing how to identify these triangles is an important part of solving many problems involving these triangles. Check out this tutorial and learn about some of the different kinds of triangles!
Add, subtract, multiply, and divide decimals to hundredths, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used.
- What are the Commutative Properties of Addition and Multiplication?
  
  The commutative property is a fundamental building block of math, but it only works for addition and multiplication. This tutorial defines the commutative property and provides examples of how to use it.
Use a pair of perpendicular number lines, called axes, to define a coordinate system, with the intersection of the lines (the origin) arranged to coincide with the 0 on each line and a given point in the plane located by using an ordered pair of numbers, called its coordinates. Understand that the first number indicates how far to travel from the origin in the direction of one axis, and the second number indicates how far to travel in the direction of the second axis, with the convention that the names of the two axes and the coordinates correspond (e.g., x-axis and x-coordinate, y-axis and y-coordinate).
- What is the Coordinate Plane?
  
  You can't graph a function or plot ordered pairs without a coordinate plane! Learn about the coordinate plane by watching this tutorial.
Use square root and cube root symbols to represent solutions to equations of the form x^2 = p and x^3 = p, where p is a positive rational number. Evaluate square roots of small perfect squares and cube roots of small perfect cubes. Know that √2 is irrational.
- What Happens When You Square a Square Root?
  
  Remember that addition and subtraction are opposite operations and multiplication and division are opposite operations? Turns out, squaring and taking the square root are opposite operations too! See why in this tutorial!
Apply the Pythagorean Theorem to find the distance between two points in a coordinate system.
- What Is the Distance Formula?
  
  If you need to find the distance between to points on the coordinate, you'll probably use the distance formula to get your answer. This tutorial introduces you to the distance formula and even shows you how to find it!
Understand that polynomials form a system analogous to the integers, namely, they are closed under the operations of addition, subtraction, and multiplication; add, subtract, and multiply polynomials.
- How Do You Multiply Binomials Using FOIL?
  
  Looking for practice using the FOIL method? This tutorial delivers! It takes you step-by-step through the FOIL method as you multiply together to binomials.
Understand that by similarity, side ratios in right triangles are properties of the angles in the triangle, leading to definitions of trigonometric ratios for acute angles.
- What is the Sine Ratio?
  
  The sine ratio is a handy ratio when you're dealing with right triangles! In this tutorial, you'll learn what the sine ratio is and how to use it to find angle measurements in a right triangle.

What is the Law of Cosines?

What is the Law of Cosines?

Note:

Keywords:

Background Tutorials

Draw points, lines, line segments, rays, angles (right, acute, obtuse), and perpendicular and parallel lines. Identify these in two-dimensional figures.

Classify two-dimensional figures based on the presence or absence of parallel or perpendicular lines, or the presence or absence of angles of a specified size. Recognize right triangles as a category, and identify right triangles.

Add, subtract, multiply, and divide decimals to hundredths, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used.

Use square root and cube root symbols to represent solutions to equations of the form x^2 = p and x^3 = p, where p is a positive rational number. Evaluate square roots of small perfect squares and cube roots of small perfect cubes. Know that √2 is irrational.

Apply the Pythagorean Theorem to find the distance between two points in a coordinate system.

Understand that polynomials form a system analogous to the integers, namely, they are closed under the operations of addition, subtraction, and multiplication; add, subtract, and multiply polynomials.

Understand that by similarity, side ratios in right triangles are properties of the angles in the triangle, leading to definitions of trigonometric ratios for acute angles.