第 16 步：为了计算我们的球应该去哪里，我们需要一个新的 y 坐标。 bally （我们当前的位置）+ rise （我们向上移动多远）就是答案！但是每次使用rise都会将球入网！我们需要使用用户猜测的斜率的上升幅度。为了获得新的上升，我们将使用坡度猜测 = 上升/运行并求解上升！
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stage.set_axis(100)
stage.create_grid_overlay(10, "grey")
stage.set_background("soccerfield")
ballx = -80
bally = random.randint(-100,100)
# sprite = codesters.Sprite("image", x, y)
ball = codesters.Sprite("soccerball", ballx, bally)
netx = 90
nety = random.randint(-100,100)
# sprite = codesters.Sprite("image", x, y)
net = codesters.Sprite("soccernet", netx, nety)
net.flip_right_left()
#sprite = codesters.Line(x-start, y-start, x-end, y-end, "color")
line = codesters.Line(ballx, bally, netx, nety, "blue")
slopeguess = float(line.ask("What is the slope of this line?"))
rise = nety - bally
run = netx - ballx
slope = rise / run
# sprite = codesters.Text("text", x, y)
sprite = codesters.Text(slope, 0, 30)
