Answer:
4√2/7
Step-by-step explanation:
Suppose cos(x)=-1/3, where pi/2≤x≤ pi
tan(2x) = sin(2x)/cos(2x)
Since sin2x = 2sinx cosx
cos 2x = 2cos²x-1
Substitute
tan(2x) = 2sinx cosx/ 2cos²x-1
Given cosx = -1/3
adjacent = -1
hyp = 3
opp = √3²-(-1)²
opp = √9-1
opp = √8
sinx = opp/hyp
sinx = √8/3
tan(2x) = 2sinx cosx/ 2cos²x-1
tan(2x) = 2(√8/3)(-1/3)/ 2(-1/3)²-1
tan2x= (-2√8/9 )÷ (2/9 - 1)
tan2x = -4√2/9 * 9/-7
tan 2x = 4√2/7
