Need in 10 mins
ASAP pls explain I’m not sure

to complete this square you have to rotate about the origin 270 degrees clockwise.

(5x-1)^2= (5x)^2-2(5x)×1+(1)^2=25x^2-10x+1

we know that

1) the inscribed angle measures half of the arc it comprises.

so

m∠dgf= > expression

2) the opposite angles in an inscribed quadrilateral are supplementary angles

so

m∠dgf=

m∠dgf=°

substitute in the expression to find the value of arc ef

therefore

the answer is

the measure of the arc ef is