ABCD is a quadrilateral.

Sides are extended as shown.

Show that x = 100°

Solution :

Given :

ABCD is a quadrilateral.

Angle ADC = 90 degree

Angle DCB = 120 degree

Now angle DAB = 70 degree (alternate angles)

We know that the interior angles of a quadrilateral is 360 degrees.

So,

∠ DAB + ∠ ABC + ∠ BCD + ∠ CDA = 360°

70° + ∠ ABC + 120° + 90 ° = 360°

∠ ABC = 360° - (70° + 120° + 90°)

∠ ABC = 360° - 280°

∠ ABC = 80°  

Now     ∠ x = 180° - ∠ ABC   (Line AB extended is 180° )

                   = 180° - 80°  

                  = 100°

Hence proved.

19.side- angle- side

20. angle- side- angle

step-by-step explanation:

which expression can be used to convert 80 us dollars (usd) to australian dollars (aud)?

1 usd = 1.0343 aud

1 aud = 0.9668 usd

step-by-step explanation:

sorry just need the points