A student solved for the radius of a circle with a circumference of 12π

Step 1: C = 2 pi r. Step 2: 12 pi = 2 pi r. Step 3: StartFraction 12 pi over 2 pi EndFraction = StartFraction 2 pi r over 2 pi EndFraction. Step 4: 6 = pi r. Step 5: StartFraction 6 over pi EndFraction = StartFraction pi r over pi EndFraction. Step 6: Solving for r, the length of the radius is StartFraction 6 over pi EndFraction centimeters. in which stept did he made the error

Step 4 is incorrect  he did not divide correctly from step3 to step 4

Step-by-step explanation:

The circumference of a circle is

C = 2 * pi *r

We know the circumference is 12 pi

12pi = 2 pi *r

Divide each side by 2 pi

12 pi/2pi = 2pi r/ 2pi

6 = r

From step 3 The student did not cancel the pi in the top and the bottom on the right hand side to isolate r

In step 4 he got 6 =pi r  instead of pi

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.

$450 i think. hope this ☺