TRY IT? Which relation is NOT a function? Explain your answer.
(1) {(1,2), (3,4),(4,5), (5,6)}
(2) {(3,1), (2,1),(1,2), (3,2)}
(3) {(4,1),(5,1),(6,1),(7,1))
(4) {(0,0), (1,1), (2,2), (3,3)}

we have three similar triangles, because each has a right angle and shares an angle.   let's write the angles in order: opposite to short leg, long leg, hypotenuse.

cab similar to bad similar to cbd

or as ratios,

ca: ab: cb = ba: ad: bd = cb: bd: cd

we also know

ac = ad + cd

(ad+cd): ab: cb = ba: ad: bd = cb: bd: cd

(ad+cd)/cb=cb/cd

we have cb=6, ad=5 and seek x=cd.

we reject the negative root and conclude x=4

answer: 4

but there’s no any figure there!

teleportation

step-by-step explanation: