Answer:
(1, 7)
Step-by-step explanation:
Substitute x = 1 into the equation for the corresponding value of y
y = 2x + 5 = (2 × 1) + 5 = 2 + 5 = 7
Solution is (1, 7)
Circumference of a circle - derivation
This page describes how to derive the formula for the circumference of a circle.
Recall that the definition of pi (π) is the circumference c of any circle divided by its diameter d. Put as an equation, pi is defined as
π
=
c
d
Rearranging this to solve for c we get
c
=
π
d
The diameter of a circle is twice its radius, so substituting 2r for d
c
=
2
π
r
If you know the area
Recall that the area of a circle is given by
area
=
π
r
2
Solving this for r
r
2
=
a
π
So
r
=
√
a
π
The circumference c of a circle is
c
=
2
π
r
Answer:
r = -3.2
Step-by-step explanation:
-0.6(r+0.2) = 1.8
Divide by -.6
-0.6/-.6(r+0.2) = 1.8/-.6
r+.2 = -3
Subtract .2 from each side
r+.2-.2 = -3-.2
r = -3.2
Answer:
15
Step-by-step explanation:
