A circle is a figure in which each point around its perimeter is an equal distance from the center. The radius of a circle is the distance between the center and any point along its perimeter. A chord is a line segment that connects any two points along its perimeter. The diameter of a circle is the length of a chord that passes through the center of the circle and equals twice the circle's radius (2r).

A right angle measures 90 degrees and is the intersection of two perpendicular lines. In diagrams, a right angle is indicated by a small box completing a square with the perpendicular lines.

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 equal sign and the answer on the other.

5y - 5 = 5 - y
5y = 5 - y + 5
5y + y = 5 + 5
6y = 10
y = \( \frac{10}{6} \)
y = 1\(\frac{2}{3}\)

You need to find the value of c so solve the first equation in terms of y:

-3c + y = 1
y = 1 + 3c

then substitute the result (1 - -3c) into the second equation:

7c + 9(1 + 3c) = 1
7c + (9 x 1) + (9 x 3c) = 1
7c + 9 + 27c = 1
7c + 27c = 1 - 9
34c = -8
c = \( \frac{-8}{34} \)
c = -\(\frac{4}{17}\)

Parallel lines are lines that share the same slope (steepness) and therefore never intersect. A transversal occurs when a set of parallel lines are crossed by another line. All of the angles formed by a transversal are called interior angles and angles in the same position on different parallel lines equal each other (a° = w°, b° = x°, c° = z°, d° = y°) and are called corresponding angles. Alternate interior angles are equal (a° = z°, b° = y°, c° = w°, d° = x°) and all acute angles (a° = c° = w° = z°) and all obtuse angles (b° = d° = x° = y°) equal each other. Same-side interior angles are supplementary and add up to 180° (e.g. a° + d° = 180°, d° + c° = 180°).