Limit Cos Sin 47C954
1. We are asked to find the limit: $$\lim_{x \to 0} \frac{\cos 4x \cdot \sin 3x}{5x}$$
2. Recall the important limit rules:
- $$\lim_{x \to 0} \frac{\sin ax}{x} = a$$
- $$\lim_{x \to 0} \cos bx = 1$$
3. Using these, rewrite the expression:
$$\frac{\cos 4x \cdot \sin 3x}{5x} = \cos 4x \cdot \frac{\sin 3x}{5x}$$
4. As $$x \to 0$$, $$\cos 4x \to 1$$.
5. For $$\frac{\sin 3x}{5x}$$, multiply numerator and denominator by 3:
$$\frac{\sin 3x}{5x} = \frac{\sin 3x}{3x} \cdot \frac{3}{5}$$
6. Using the limit rule, $$\lim_{x \to 0} \frac{\sin 3x}{3x} = 1$$.
7. Therefore, the limit is:
$$1 \cdot \frac{3}{5} = \frac{3}{5}$$
**Final answer:** $$\frac{3}{5}$$ which corresponds to option C.