Find (a) the area and (b) the circumference of each circle using π=3.14. round to the hundredths' place. 1. the diameter of the circle is 9.5cm. 2. the radius of the circle is 4cm.

area = pi x r^2

circumference = 2x pi x r or pi x d

1st one diameter = 9.5 cm

so radius = 9.5/2 = 4.75

area = 3.14 x 4.75^2 = 70.85 square cm

circumference = 3.14 x 9.5 = 29.83 cm

2nd one radius = 4

area = 3.14 x 4^2 = 50.25 square cm

circumference = 2 x 3.14 x 4 = 25.12 cm

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional

solve systems of equations by graphing. a system of linear equations contains two or more equations e.g. y=0.5x+2 and y=x-2. the solution of such a system is the ordered pair that is a solution to both equations. to solve a system of linear equations graphically we graph both equations in the same coordinate system