If ab and cd are congruent what is the measure of chord ab

the measure of cord AB will be same as cord CD that is 21 units

because these both are congruent

for this case we have the following expression:

to solve, we rewrite the expression as:

we apply double c and we have:

thus, the quotient is 48.

so, patel found a wrong ratio and the multiplication was incorrect.

option d