Need help proving the cos(a+b) = (cos a)(cos b)(sin a)(sin b) trigonometric identity? This free video lesson will show you how. From Ramanujan to calculus cocreator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps (or just finish your homework or study for that next big test). With this installment from Internet pedagogical superstar Salman Khan's series of free math tutorials, you'll learn how to verify this fundamental trigonometric identity.
 Hot
 Latest

How To: Find the Percent Given Two Numbers

How To: Find a number given Its percent

How To: Do long division without a calculator

How To: Use ">" (greater than) and "<" (less than) symbols

How To: Find the slope of a line given 2 points with fractions

How To: Find a missing coordinate given: coordinate & equation

How To: Find the coordinate of a point

How To: Solve percentages without a calculator

How To: Convert fractions to percents in two steps

How To: Calculate Faster Than a Calculator

How To: Calculate the height and volume of a pyramid

How To: Find the formula of a piecewise function given a graph

How To: Convert Fahrenheit to Celsius with a formula

How To: Identify characteristics of a sample during a survey

How To: Calculate the area of a parallelogram

How To: Spend Money on a Graphing Calculator? Nah—Just Use This WebBased TI Emulator

How To: Find a missing side of a triangle, similar to another

How To: Find the slope from a set of points

How To: Do long division with different approaches

How To: Remember "greater than" & "less than" symbols

How To: Find the Percent Given Two Numbers

How To: Find a number given Its percent

How To: Do long division without a calculator

How To: Use ">" (greater than) and "<" (less than) symbols

How To: Find the slope of a line given 2 points with fractions

How To: Find a missing coordinate given: coordinate & equation

How To: Find the coordinate of a point

How To: Solve percentages without a calculator

How To: Convert fractions to percents in two steps

How To: Calculate Faster Than a Calculator

How To: Calculate the height and volume of a pyramid

How To: Find the formula of a piecewise function given a graph

How To: Convert Fahrenheit to Celsius with a formula

How To: Identify characteristics of a sample during a survey

How To: Calculate the area of a parallelogram

How To: Spend Money on a Graphing Calculator? Nah—Just Use This WebBased TI Emulator

How To: Find a missing side of a triangle, similar to another

How To: Find the slope from a set of points

How To: Do long division with different approaches

How To: Remember "greater than" & "less than" symbols
Be the First to Comment
Share Your Thoughts