Question:

COSΘ= x/r COSΘ= -7/25

Its in Quadrant III so X and Y are Negative

X= -7 R= 25

r=(x^2 + y^2)^1/2

25=((-7)^2 + y^2)^1/2

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My Work

25=((-7)^2 + y^2)^1/2

25=(49 + y^2)^1/2

25= 7+y

18= y which is incorrect

The math lab says this is the correct answer Y=-24 but i get something different. Can anyone help me solve this or explain where i went wrong.