Cong thuc toan

Question 1

công thức nhân đôi

Answer 1

Sin2a= 2cosasina
cos2a= cos^2a-sin^2a=2cos^a-1=1-sin^2a
tan2a= 2tana/1-tan^2a

Question 2

cong thuc cong

Answer 2

cos(a-b)=cosacosb+sinasinb
cos(a+b)=cosacosb-sinasinb
sin(a-b)=sinacosb-cosasinb
sin(a+b)=sinacosb+cosasinb
tan(a-b)=tana-tanb/1+tanatanb
tan(a+b)=tana+tanb/1-tanatanb