13. The isosceles triangle EJF is one of an unknown number of isosceles triangles from the original arch. Each isosceles triangle had the same vertex angle as triangle EJF. The sum of the vertex angles equals 180°. (2 points, one for the correct equation, one for the correct solution.)

Let x = the number of isosceles triangles.

Fill in the equation with your answer from Q12 and solve for x.

___ • x = 180

x = 23.78

step-by-step explanation:

191 students play sports and ninety-seven 10th graders were surveyed.

step-by-step explanation:

(b) 240

step-by-step explanation:

first, we use the pythagorean formula using the given side lengths to find x. then we use x to find the side lengths. then we add the side lengths to find the perimeter.

pythagorean theorem formula:

a^2 + b^2 = c^2

(x - 20)^2 + (x - 40)^2 = x^2

x^2 - 40x + 400 + x^2 - 80x + 1600 = x^2

x^2 -120x + 2000 = 0

(x - 100)(x - 20) = 0

x - 100 = 0 or x - 20 = 0

x = 100 or x = 20

we see that the solution x = 20 must be discarded because it will give a negative side length and a side length of 0. the only valid solution is x = 100.

perimeter = sum of the lengths of the sides

perimeter = x + x - 20 + x - 40

perimeter = 3x - 60

replace x with 100.

perimeter = 3(100) - 60

perimeter = 300 - 60

perimeter = 240

144.50

step-by-step explanation:

21.5 x 13.4=288.10 divide by 2