V =2R/R-r solve for r

Ac contractor is building a new subdivision outside of the city. he has started work on the first street and is planning on the other streets to run in a direction parallel to the first. the second street will pass through (-2,4) find the equation of the location of the second street in standard form. a.2x+y=2 b. x-y=2 c.2x+y=2 d.x+y=2

Geometry in the diagram, ∠abc is a right angle. ∠dbc = 30°27'40". find the measure of ∠abd.

Can you me find the missing length. i attached an image.