Problems on Trigonometry Tangent

Problems on Trigonometry Tangent : How to find the equation of tangent to circle of equation x²+y²=4 at point (0,2) & (2,0)? Solution: x² + y² = 4 Differentiating and equating to zero: 2x + 2y(dy/dx) = 0 2y(dy/dx) = –2x dy/dx = –x/y At pt: (0, 2) m = dy/dx = –x/y = –0/2 = 0 Horizontal line: Equation of tangent line is y = 2 At pt: (2, 0) m = dy/dx = –x/y = –2/0 ..... undefined Vertical line: Equation of tangent line is x = 2 Equation of tangent line (x,y)=(2,2)