loga x = 
sin2x + cos2x = 1
1 + tan2x = sec2x
1 + cot2x = csc2x
sin 2x = 2 sin x cos x
cos 2x = cos2x - sin2x
sin2x = ½(1- cos 2)
cos2x = ½(1+ cos 2)
Volume of a right circular cylinder = 
r2h
Volume of a cone = 
r2h
Volume of a sphere = 
r3