---
source: knowledge_base
topic: trigonometry
class_level: class_10
difficulty: intermediate
---

Trigonometry:
sin^2(x)+cos^2(x)=1. tan(x)=sin(x)/cos(x).
sin(A+B)=sinA*cosB+cosA*sinB. cos(A+B)=cosA*cosB-sinA*sinB.
sin(2x)=2sin(x)cos(x). cos(2x)=cos^2(x)-sin^2(x).
Values: sin30=1/2, sin45=sqrt(2)/2, sin60=sqrt(3)/2, sin90=1.
Law of Sines: a/sinA=b/sinB=c/sinC. Law of Cosines: c^2=a^2+b^2-2ab*cosC.