中等MATH-GEOM-008
How do the line x + y = 2 and the circle x^2 + y^2 = 2 meet?
A. They touch at exactly one point✓ 答案
B. They intersect at two points
C. They do not meet
D. They intersect at the origin
解說
The distance from the origin to the line is 2/√2 = √2, equal to the radius √2, so the line is a tangent. The origin is not on the line, because 0 + 0 ≠ 2.