Here's another way...
Let's extend
WZ to point A,
XY to point B,
ZY to point C,
WX to point D, and
YX to point E
Like this:
m∠XWZ = m∠YZA | _____ | because corresponding angles are congruent. |
m∠YZA = m∠CYB |
| because corresponding angles are congruent. |
m∠CYB = m∠XYZ | because vertical angles are congruent. | |
Therefore |
| |
m∠XWZ = m∠XYZ | by the transitive property of congruence. | |
Likewise... |
| |
m∠WZY = m∠XYC | because corresponding angles are congruent. | |
m∠XYC = m∠EXD |
| because corresponding angles are congruent. |
m∠EXD = m∠WXY | because vertical angles are congruent. | |
Therefore |
| |
m∠WZY = m∠WXY | by the transitive property of congruence. |
Add the two equations together to get
2a = 8b
a = 4b
Substitute this value in for a in the first given equation.
4b + (4b)b2 = 40b
4b + 4b3 = 40b
Subtract 40b from both sides of the equation.
4b3 - 36b = 0
Factor b out of the terms on the left side.
b(4b2 - 36) = 0
Factor 4b2 - 36 as a difference of squares.
b(2b + 6)(2b - 6) = 0
Set each factor equal to zero and solve for b
b = 0 | ____or____ | 2b + 6 = 0 | ____or____ | 2b - 6 = 0 |
2b = -6 |
| 2b = 6 | ||
b = -3 | b = 3 |
If b = 0 then a = 4b = 4(0) = 0 so (0, 0) is a solution.
If b = -3 then a = 4b = 4(-3) = -12 so (-12, -3) is a solution.
If b = 3 then a = 4b = 4(3) = 12 so (12, 3) is a solution.