For what values of the variables must ABCD be a​ parallelogram?

5 y degrees5y°
5 x degrees5x°
left parenthesis y plus 96 right parenthesis degrees(y+96)°
left parenthesis 6 x minus 12 right parenthesis degrees(6x−12)°

A
B
C
D

1 answer

To determine the values of the variables \( x \) and \( y \) that will make quadrilateral ABCD a parallelogram, we need to use the property that opposite angles of a parallelogram are equal.

Let’s assign the angles as follows:

  • Angle A is \( 5y^\circ \)
  • Angle B is \( 5x^\circ \)
  • Angle C is \( (y + 96)^\circ \)
  • Angle D is \( (6x - 12)^\circ \)

Since ABCD is a parallelogram, we need to satisfy the following conditions:

  1. \( A + C = 180^\circ \)
  2. \( B + D = 180^\circ \)

Let's establish the equations based on these angles:

Equation 1:

From angles A and C: \[ 5y + (y + 96) = 180 \]

Combining like terms: \[ 6y + 96 = 180 \] Subtract 96 from both sides: \[ 6y = 84 \] Now, divide by 6: \[ y = 14 \]

Equation 2:

From angles B and D: \[ 5x + (6x - 12) = 180 \]

Combining like terms: \[ 11x - 12 = 180 \] Now, add 12 to both sides: \[ 11x = 192 \] Divide by 11: \[ x = \frac{192}{11} \approx 17.45 \]

Conclusion:

Thus, for quadrilateral ABCD to be a parallelogram, the values of the variables must be:

  • \( y = 14 \)
  • \( x = \frac{192}{11} \) or approximately 17.45.