Question 958720
From pythagoras theorem
(AC)^2=(AB)^2+(BC)^2
(13)^2=(AB)^2+(-12)^2
(AB)^2=(13)^2-(-12)^2 =169-144=25
(AB)^2=25 =>AB=SQRT(25)=5
AB=5
since theta is in 3rd quadrant
cosec theta =- 13/5
tan theta = -5/-12=5/12