You need the slant height to find the lateral area of the cone, so using the equation l = √h²+r², you plug in the height for h, the radius for r, and l is the slant height.
l =√12²+5²
l = √144 + 25
l = √169
l = 13
Now that you have the slant height, simply multiply that by the radius and you'll get the lateral area in terms of pi.
