



 
Hi Paula. The distance from the origin to any point (x, y) is sqrt(x^{2} + y^{2}). If you aren't convinced, then draw a line from the origin to the point, from the point straight up (or down) to the xaxis and from there to the origin. That is a right triangle and Pythagoras' Theorem should convince you that the hypotenuse, which is the distance from the origin to the point, is sqrt(x^{2} + y^{2}). You know the distance and you know the value x. This gives you the hypotenuse and one side length and you just need to find the y value. If you do the calculation 15^{2} = 9^{2} + y^{2} What values of y work? Cheers,  


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