Option C:
[tex]\sqrt{7^2+15^2}=x[/tex] is used to solve the fallen part of the tree.
Solution:
Given data:
One side length = 7 ft
Base length = 15 ft
To find which equation could be used to find the length of the fallen part.
Let the fallen part be x.
The image is look like a right triangle.
Using Pythagoras theorem,
In a right angled triangle, square of the hypotenuse is equal to the sum of the squares of the other two sides.
[tex]\text{Height} $^{2} + \text{Base} $^{2}=$ Hypotenuse $^{2}$[/tex]
[tex]7^2+15^2=x^2[/tex]
Taking square root on both sides of the equation.
[tex]\sqrt{7^2+15^2}=\sqrt{x^2}[/tex]
[tex]\sqrt{7^2+15^2}=x[/tex]
This equation is used to solve the fallen part.
Option C is the correct answer.
Hence [tex]\sqrt{7^2+15^2}=x[/tex] is used to solve the length of the fallen part of the tree.
