Given a||b ,and cis not parallel to a or b which of the following are true ? choose all answers that are correct.

Options B and D are true.

Step-by-step explanation:

See the diagram attached.

Line a and b are parallel and line c is not parallel to them.

There is a transverse line and this line forms the angles 1 to 12.

Now, option A gives ∠ 8 + ∠ 10 = 180° which can not be true as line c is not parallel to line b.

Option B gives ∠4 + ∠ 6 = 180° which is true because line a is parallel to line b and ∠ 4 and ∠ 6 are interior supplementary angles.

Option C gives ∠ 1 + ∠ 11 = 180° which can not be true as line c is not parallel to line a.

Option D gives ∠3 + ∠ 5 = 180° which is true because line a is parallel to line b and ∠ 3 and ∠ 5 are interior supplementary angles.

Therefore, options B and D are true. (Answer)

(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