$A\ =\ \frac{1}{2}bh$

$A\ =\ \frac{1}{2}\left(a+b\right)h$

$A\ =\ \frac{a+b}{2}\times h$

$A=\frac{1}{2}\pi r^2$

 $a=2,\ b=3,\ c=4$  

 $a=-2,\ b=-3,\ c=4$  

 $a=2,\ b=-3,\ c=-4$  

 $a=2,\ b=-3,\ c=4$  

$\frac{a}{\cos\ A}=\ \frac{b}{\cos B}=\frac{c}{\cos\ C}$

$a^2=b^2+c^2-2bc\cos A$

$a^2=b^2-c^2+2ab\cos C$

$\cos A=\frac{b}{c}$

$a^2=b^2+c^2-2bc\sin A$

$\frac{a}{\sin A}=\ \frac{b}{\sin B}=\ \frac{c}{\sin C}$

$\sin A=\frac{b}{c}$

$\frac{a}{\sin A}=\ \frac{\sin B}{b}$

any triangle

any triangle where you know two of the sides

any right-angled triangle

only when you know the hypotenuse and one other side

$a^2=\left(b+c\right)^2$

$a^2=b^2+c^2$

$a=b+c$

$a^2=bc^2$

 $V=lbh$  

 $V=\pi h$  

 $V=r^2h$  

 $V\ =\ \pi r^2h$  

the volume of a sphere

the surface area of a pyramid

the volume of a pyramid

the volume of a prism

 $D\div T$  

 $T\div D$  

 $D\times T$  

 $D+T$  

$A=\frac{1}{2}ab\cos C$

$A=\frac{1}{2}ab\sin C$

$A=ab\sin C$

$A=2ab\sin C$

$x=\frac{2b\pm\sqrt{b^2-4ac}}{2a}$

$x=\frac{a\pm\sqrt{b^2-ac}}{2a}$

$x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}$

$x=\frac{-b\pm\sqrt{b^2+4ac}}{2a}$

area of a circle

area of a semi-circle

volume of a cylinder

circumference of a circle

opp / adj

adj / hyp

hyp / opp

opp / hyp

cos

sin

tan 

$D=\frac{M}{V}$

$D=MV$

$V=\frac{D}{M}$

$V=DM$

$V=\frac{lb}{h}$

$V=lh$

$V=lbh$

$V=\frac{1}{2}lbh$