**Interactive distance formula. Click and drag points to see formula in action


A+    A−    B  
Home
Algebra
Math Games
Geometry
Private Tutors
Interactive
Trigonometry
Jobs
Teacher Resources

AddThis Social Bookmark Button

Angle Difference Formula

How to use formula to express exact values

The angle difference identities take two different formulas
  • sin(A − B) = sinAcosB − cosAsinB
  • cos(A − B) = cosAcosB + sinAsinB
These formulas allow you to express the exact value of trigonometric expressions that you could not otherwise express. Consider the cos(15°). Unlike the cos(60°) which can be expressed as ½, the cos(15°) cannot simply be represented as a rational expression. However, the angle difference formula allows you to reprsent the exact value of this function Picture of angle difference formula

Top
AddThis Social Bookmark Button