suppose you choose a real number x from the interval [2, 10] with a density function of the form f(x) = c/x , where c is a constant find the expectation e(x) and variance var(x) of x

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

c. 6tan80

step-by-step explanation:

if im not mistaking its

step-by-step explanation: