We are asked to find the limit of the function $\frac{\tan(x^2 + y^2)}{x^2 + y^2}$ as $(x, y)$ approaches $(0, 0)$.
AnalysisLimitsMultivariable CalculusTrigonometric FunctionsL'Hopital's RuleSmall Angle Approximation
2025/4/30
1. Problem Description
We are asked to find the limit of the function as approaches .
2. Solution Steps
Let . Then as , we have . Thus, we can rewrite the limit as:
\lim_{(x,y) \to (0,0)} \frac{\tan(x^2 + y^2)}{x^2 + y^2} = \lim_{u \to 0} \frac{\tan(u)}{u}
We know that . Thus, we have
\lim_{u \to 0} \frac{\tan(u)}{u} = 1
To show this, we can use L'Hopital's Rule:
\lim_{u \to 0} \frac{\tan(u)}{u} = \lim_{u \to 0} \frac{\sec^2(u)}{1} = \sec^2(0) = \frac{1}{\cos^2(0)} = \frac{1}{1^2} = 1
Alternatively, we can use the small angle approximation for where as .
\lim_{u \to 0} \frac{\tan(u)}{u} = \lim_{u \to 0} \frac{u}{u} = 1
3. Final Answer
The limit is 1.