Consider the equation of a circle x^2-2x+y^2-4y-4=0. If the line 2x-y+a=0 is its diameter. Then find the value of a.

a=0

Step-by-step explanation:

x²-2x+y²-4y-4=0

(x²-2x+1)+(y²-4y+4)-9=0

(x-1)² + (y-2)² = 3²

Center: (1,2)     radius: 3

(1,2) on line 2x-y+a=0

2*1 - 2 + a = 0

a = 0

d) 48

step-by-step explanation:

16,32,48,64,80,96,112,128,144,160,176,192,208,224,240,256,272,288,304,320,336

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