The circumference of a circle is 60 pi cm. what is the radius of the circle?
a) 90cm
b) 60cm
c) 120cm
d) 30cm

D

Step-by-step explanation:

The formula for the circumference of a circle is 2r. So if we know that C=60then we can trace our steps back. We are given that pi remains constant so we are left with the 2r from the formula and a 60. 60/2 =30.

The radius is 30cm

c. y = 1/4 x + 5

step-by-step explanation:

first, put the equation of the line on the graph into slope-intercept form

(y = mx + b):   y = -4x + 8

second, a perpendicular line has to have "an opposite/reciprocal slope" to the original slope. so, find the "m" value in your original equation (it's -4, right? )

original slope: m = -4   perpendicular slope: change the sign to its opposite and find the reciprocal ("flip" the number)

new slope is now positive (b/c the original slope was negative 4), and it's 1/4 (not the original slope of 4 or 4/1)