The circumference of a circle is the distance around its perimeter and equals π (approx. 3.14159) x diameter: c = π d. The area of a circle is π x (radius)² : a = π r².

The surface area of a cylinder is 2πr² + 2πrh:

sa = 2πr² + 2πrh
sa = 2π(1²) + 2π(1 x 4)
sa = 2π(1) + 2π(4)
sa = (2 x 1)π + (2 x 4)π
sa = 2π + 8π
sa = 10π

To solve this equation, repeatedly do the same thing to both sides of the equation until the variable is isolated on one side of the > sign and the answer on the other.

4b - 2 > 8 + 8b
4b > 8 + 8b + 2
4b - 8b > 8 + 2
-4b > 10
b > \( \frac{10}{-4} \)
b > -2\(\frac{1}{2}\)

An exterior angle of a triangle is equal to the sum of the two interior angles that are opposite:

d° = b° + c°

To find angle c, remember that the sum of the interior angles of a triangle is 180°:

180° = a° + b° + c°
c° = 180° - a° - b°
c° = 180° - 69° - 24° = 87°

So, d° = 24° + 87° = 111°

A shortcut to get this answer is to remember that angles around a line add up to 180°:

a° + d° = 180°
d° = 180° - a°
d° = 180° - 69° = 111°

To solve this equation, isolate the variable for which you are solving (b) on one side of the equation and put everything else on the other side.

-5b + y = 9b - 7y + 3
-5b = 9b - 7y + 3 - y
-5b - 9b = -7y + 3 - y
-14b = -8y + 3
b = \( \frac{-8y + 3}{-14} \)
b = \( \frac{-8y}{-14} \) + \( \frac{3}{-14} \)
b = \(\frac{4}{7}\)y - \(\frac{3}{14}\)