Chapter 3 - Vectors and Coordinates Systems - Exercises and Problems - Page 77: 5

The y-component of the vector is 8 m.

Since the vector is in the first quadrant, the y-component of the vector is positive. Therefore, $x^2+y^2 = (10~m)^2$ $y^2 = (10~m)^2 - x^2$ $y = \sqrt{(10~m)^2 - x^2}$ $y = \sqrt{(10~m)^2 - (6~m)^2}$ $y = 8~m$ The y-component of the vector is 8 m.