Answer:

Step-by-step explanation:
Given that,
Radius of a cone, r = 13 cm
Slant height of the cone, l = 20 cm
We need to find the surface area of the cone. The formula for the surface area of the cone is given by :

Put all the values,

So, the surface area of the cone is
.
Using the law of cosine for Triangle KJL, we can write:

Using the values of k,j and l, we can write:

Rounding to nearest integer, the measure of angle J will be 48 degrees.
So option B gives the correct answer