Geometry Revisited:Power of a problem: can't understand

[rakeen]

.................i was just thinking should i pm ppl for probs that i cant understand, or shld i post those prob too? and my problm is stated in the pic

[fermat's rebirth]

i don't know surely bt i think this would work......let us assume that the secant is AB....then the tangent at A is the limit when point B approximates or tends to A i mean when the secant starts to limitize(not sure about vocabulary) itself to its limiting value a very smaaaaaaaaaaaaaaaaaaaalllllllllllllllllllllll value....................i think

[rakeen]

hmm..thanx. i think i got that