The straight line y=x+k and the curve x=√( 1-y? ), these two images have one thing in common, and find the range of K.

Solution: curve x=√( 1-y? ) is a semicircle with the center of the circle at the origin, with radius = 1, located on the right side of the y axis,-1≦y≦ 1, 0≦x≦ 1.

Y=x+k is a straight line with a slope of 1, which is 45 with the positive direction of the X axis, and k is the intercept of the straight line on the Y axis; It is not difficult to judge from the images: the range of K that makes two images have only one thing in common is-1