A certain coin is a circle with diameter 18mm. What is the exact area of either face of the coin?

81pi mm^2

Step-by-step explanation:

The radius is 1/2 the diameter, and is used in finding the area of a circle.

The formula for this is

A = pi(r)^2

So the formula you would use is

A = pi (9)^2

= 81pi

Usually teachers accept it in terms of pi, but if not, you can use 3.14 and multiple it.

I hope this helped!

5x + 3y = - 4

step-by-step explanation:

the equation of a line in standard form is

ax + by = c ( a is a positive integer and b, c are integers )

express the line first of all in slope- intercept form

y = mx + c ( m is the slope and c the y-intercept )

to calculate m use the gradient formula

m = ( y₂ - y₁ ) / ( x₂ - x₁ )

with (x₁, y₁ ) = (7, - 3) and (x₂, y₂ ) = (4, - 8)

m = = -

y = - x + c ← is the partial equation

to find c substitute either of the 2 points into the partial equation

using (4, - 8 ), then

- 8 = - + c ⇒ c = -

y = - x - ← in slope-intercept form

multiply all terms by 3 to eliminate the fractions

3y = - 5x - 4 ( add 5x to both sides )

5x + 3y = - 4 ← in standard form