To find the lateral area of a cone, we need to know the radius of the base and the slant height.
In this question, the radius of the base is given as 140 m, but the slant height is not provided. However, we are given that it forms a right angle with a line segment of length 50 m.
To find the slant height of the cone, we can use the Pythagorean theorem. The slant height, the radius, and the height form a right-angled triangle, where the height is the altitude of the cone. Let's call the slant height "l", the height "h", and the radius "r".
According to the Pythagorean theorem, the sum of the squares of the two shorter sides of a right-angled triangle is equal to the square of the hypotenuse. In our case, this can be expressed as:
l^2 = r^2 + h^2
We are given that the length of the line segment forming a right angle with the slant height is 50 m, so we have:
l^2 = r^2 + 50^2
Substituting the value of the radius (140 m) into the equation, we get:
l^2 = 140^2 + 50^2
Now let's calculate the value of l using a calculator:
l^2 = 19600 + 2500
l^2 = 22100
Taking the square root of both sides to solve for l:
l = √22100
Now that we have the slant height, we can calculate the lateral area of the cone. The formula for the lateral area of a cone is given by:
Lateral Area = π * r * l
Substituting the values of the radius and slant height into the formula, we get:
Lateral Area = π * 140 * √22100
To find the approximate value of the lateral area to the nearest whole number, we can use a calculator:
Lateral Area ≈ 3.14159 * 140 * √22100
Round the result to the nearest whole number:
Lateral Area ≈ 3.14159 * 140 * 148.668
Lateral Area ≈ 65203.413
As for the answer options provided, none of them match the calculated value of approximately 65203. Therefore, none of the options A, B, C, or D are correct.