# pre-calculus

tanx= -12/5 x in quadrant 2
find;
sin2x=
cos2x=
tan2x=

1. draw a sketch of x y axis system

x = -5
y = 12
hypotenuse = 13

sin x = 12/13
cos x = -5/13
tan x = -12/5
now use 2x formulas
for example
sin 2x = 2 sin x cos x = 24/13 * -5/13
= -120/169

posted by Damon

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