Rumus Identitas Trigonometri

\[sin^2x + cos^2 x = 1\] \[sin^2x = 1-cos^2x\] \[cos^2x = 1-sin^2x\] \[tan \ x =\frac{sin \ x}{cos \ x}\] \[cot \ x = \frac{cos \ x}{sin \ x}\] \[sec \ x = \frac{1}{cos \ x}\] \[cosec \ x = {1} + {sin} \ x\] \[sec^2 \ x = tan^2 \ x +1\] \[cosec^2 \ x = cot^2x + 1\]

\[cos (α + β) = cos \ α \cdot cos β – sin \ α \ sin \ β\] \[cos (α – β) = cos \ α \cdot cos β + sin \ α \ sin \ β\] \[sin (α + β) = sin \ α \cdot cos β + cos \ α \ sin \ β\] \[sin (α – β) = sin \ α \cdot cos β – cos \ α \ sin \ β\] \[tan (α + β) = \frac{tan \ α + tan β} {1- tan \ α \ tan \ β}\] \[tan (α – β) = \frac{tan \ α + tan β} {1+ tan \ α \ tan \ β}\]

\[sin \ 2α = 2 \ sin \ α \ cos \ α\] \[cos \ 2α = cos^2α – sin^2 \ α\] \[\ \ \ \ \ = 2 \ cos^2α-1\] \[\ \ \ \ \ = 1-2 \ sin^2α\] \[sin \ 3α = 3 \ sin \ α – 4 \ sin^2 α\] \[tan \ 2α = \frac{2 \ tan \ α}{1-tan^2α}\] \[cos \ 3α = 4 \ cos^2 α – 3 \ cos α\]

\[sin \ α \ cos \ β= \frac{1}{2}{sin(α +β) + sin(α -β)}\] \[cos \ α \ sin \ β= \frac{1}{2}{sin(α +β) – sin(α -β)}\] \[cos \ α \ sin \ β= \frac{1}{2}{cos(α +β) + cos(α -β)}\] \[sin \ α \ sin \ β= \frac{1}{2}{cos(α +β) – cos(α -β)}\]

\[sin \ A = \frac{sisi \ tegak \ lurus}{sisi \ miring}\] \[sin \ A = \frac{5}{13}\] \[cos \ A = \frac{alas}{sisi \ miring}\] \[cos \ A = \frac{12}{13}\]

\[tan \ A =\frac{sin \ x}{cos \ x}\] \[tan \ A =\frac{\frac{5}{13}}{\frac{12}{13}}\] \[tan \ A = \frac{5}{13} \cdot \frac{13}{12}\] \[tan \ A = \frac{5}{12}\]