SOME IMPORTANT TRIGONOMETRY FORMULA | IMPORTANT T- RATIO FORMULA

 (1). Sin(θ) = p/h

(2). Cos(θ)  =  b/h

(3). Tan(θ) = Sin(θ)/Cos(θ)

(4). Cot(θ) = Cos(θ)/Sin(θ) 

(5) .Sec(θ) = 1/ Cos(θ) 

(6).Cosec(θ) = 1/ Sin(θ) 

(7) . Sin2(θ)+Cos2(θ) =1

(8).  Sin2(θ)  = 1-Cos2(θ)

(9).  Cos2(θ) = 1-Sin2(θ)

(10).  Sin(2θ) = 2Sin(θ)Cos(θ)

(11). Sin(θ) = 2Sin(θ/2)Cos(θ/2)

(12). Cos(2θ) = Cos2(θ) - Sin2(θ)

(13). Cos(2θ) =  1 - 2Sin2(θ)

(14). 1-Cos(2θ)  =  2Sin2(θ)

(15). Cos(2θ) = 2Cos2(θ) -1

(16). 1+Cos(2θ)  =  2Cos2(θ)

(17). 1+Cos(θ)  =  2Cos2(θ/2)

(18). 1 + tan2(θ) = Sec2(θ)

(19). 1 + Cot2(θ) = Cosec2(θ)

(20). tan2(θ) =  2 tan(θ) /1-tan2(θ)

(21). Sin(A+B)=sin(A) cos(B)+Cos(A)sin(B)

(22). Sin(A- B)=sin(A)cos(B)- cos(A) sin(B)

(23). Cos(A+B) = cosA cosB - SinA SinB

(24). Cos(A- B) = cosA CosB + SinA SinB

(25) .sinC+ sinD =2 sin(C+D/2) cos(C- D/2)

(26).sinC- sinD =2 sin(C- D/2)  cos(C+D/2)

(27). Cos C + Cos D =2 cos(C+D/2)cos(C -D /2)

(28).CosC- CosD = 2sin(C- D/2)  sin(C+D/2)