Question

Mia plans to cover a portion, ADC, of a collage with two triangular pieces of cardboard. She cuts out the first piece of cardboard BCD, as shown below.
What is the length of side AB of the second piece of cardboard, ABD, which Mia has to cut?

Answer 1

20*tan(60) - 20*tan(30)

Answer 2

use similar approach as used earlier

Answer 3

again he beat me to the answer

Answer 4

These are the answer choices, though:
11.5 cm
19.3 cm
23.1 cm
34.6 cm

Answer 5

23.1cm

Answer 6

oh, okay . thank you :)