A circular plate has circumference 20.7 inches. What is the area of this​ plate? Use 3.14 for

A ≈ 34.1 in²

Step-by-step explanation:

Using the formulas of area & circumference:

A = πr2

C = 2πr

Solving for A:

A = C2

4·π = 20.72

4·π = 34.09815 in²

4·π ≈ 34.1 in²

step-by-step explanation:

no, her answer is not correct.   we square the lengths of all sides and then determine whether the pythagorean theorem holds here:

9² + 15² = 306.   this is not equal to the square of the longest side ( that square being 395.   answer c is correct.

second option

step-by-step explanation:

the measures of a triangle equal 180. use that to find x.

2x+3x+4x=180

9x=180

9x/9=180/9

x=20

now you know x, you know angle a is 40°, angle b is 60°, angle c is 80°.

because angle a is 40°, the first option doesn't work.

because angle b is 60°, the second option does work.

when you add angle a and b, you get 100°. complementary means it equals 90°, so the third option doesn't work.

when you add angle a and c, you get 120°, which is not 100.