The number of values of \( C \) such that starting line \( y=4 x+c \) touches the curves \( \mathrm{x}^{2}+4 \mathrm{y}^{2}=4 \)
Step-by-step Solution:
Step 1: General Condition for Tangency
For a line \( y = mx + c \) to touch the ellipse \( \frac{x^2}{a^2} + \frac{y^2}{b^2} = 1 \), the condition is:
\[
c^2 = a^2 m^2 + b^2
\]
Step 2: Identify Given Parameters
The given equation of the ellipse is:
\[
x^2 + 4y^2 = 4
\]
Rewriting it in standard form:
\[
\frac{x^2}{4} + \frac{y^2}{1} = 1
\]
Comparing with the standard equation \( \frac{x^2}{a^2} + \frac{y^2}{b^2} = 1 \), we get:
\[
a^2 = 4, \quad b^2 = 1
\]
The given line is:
\[
y = 4x + c
\]
So the slope is \( m = 4 \).
Step 3: Apply Tangency Condition
Using the tangency condition:
\[
c^2 = a^2 m^2 + b^2
\]
Substituting the values:
\[
c^2 = (4)(16) + 1
\]
\[
c^2 = 64 + 1 = 65
\]
\[
c = \pm \sqrt{65}
\]
Step 4: Conclusion
Since there are two values of \( c \) (i.e., \( \sqrt{65} \) and \( -\sqrt{65} \)), the correct answer is 2.
Thus, the correct option is A (2).