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Multiple Choice
Given a curve and a contour map of a function whose gradient is continuous, which of the following statements is true about the direction of the gradient vector of at a point on ?
A
The gradient vector of at a point on is perpendicular to the contour line passing through that point.
B
The gradient vector of at a point on always points toward the origin.
C
The gradient vector of at a point on is tangent to the contour line passing through that point.
D
The gradient vector of at a point on is zero.
Verified step by step guidance
1
Step 1: Understand the concept of a gradient vector. The gradient vector of a function f, denoted as ∇f, points in the direction of the greatest rate of increase of the function. It is perpendicular to the level curves (contour lines) of the function at any given point.
Step 2: Recall the relationship between contour lines and the gradient vector. Contour lines represent points where the function f has the same value. The gradient vector is always perpendicular to these contour lines because it points in the direction of the steepest ascent, which is orthogonal to the direction of no change (the contour line).
Step 3: Analyze the given options. The correct statement is: 'The gradient vector of f at a point on C is perpendicular to the contour line passing through that point.' This aligns with the mathematical property of gradient vectors and contour lines.
Step 4: Eliminate incorrect options. The gradient vector does not always point toward the origin, as its direction depends on the function f and its rate of change. It is not tangent to the contour line, as this would imply no change in the function value. The gradient vector is not zero unless the function is constant at that point.
Step 5: Conclude that the correct answer is based on the fundamental property of gradient vectors being perpendicular to contour lines, which is a key concept in multivariable calculus.