M=(-3; 4) is the midpoint of the larger circle and a point on the smaller circle with midpoint O(0; 0) - NSC Mathematics - Question 4 - 2020 - Paper 2
Question 4
M=(-3; 4) is the midpoint of the larger circle and a point on the smaller circle with midpoint O(0; 0). From N(-11; p), a tangent is drawn to the larger circle by T ... show full transcript
Worked Solution & Example Answer:M=(-3; 4) is the midpoint of the larger circle and a point on the smaller circle with midpoint O(0; 0) - NSC Mathematics - Question 4 - 2020 - Paper 2
Step 1
4.1 Bepaal die vergelyking van die klein sirkel.
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Answer
Om die vergelyking van die klein sirkel te bepaal, weet ons dat die sirkel met sentrum O(0; 0) en 'n straal van 5 kan geskryf word as: x2+y2=25
Step 2
4.2 Bepaal die vergelyking van die sirkel met middelpunt M in die vorm $(x-a)^2 + (y-b)^2 = r^2$.
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Answer
Hier is die middelpunt M=(-3; 4). Dit beteken:
a=−3
b=4
Die straal kan bereken word as die afstand van T = (-11; 4) tot M.
Afstand formule:
4.3 Bepaal die vergelyking van NM in die vorm $y=mx+c$.
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Die punt N=(-11; p) en M=(-3; 4) word gebruik om die helling m te bereken.
Die formule vir die helling is: m = rac{y_2 - y_1}{x_2 - x_1} = rac{4 - p}{-3 - (-11)} = rac{4 - p}{8}
Die vergelyking kan dan geformuleer word as: y - 4 = rac{4 - p}{8}(x + 3)
Step 4
4.4 Bereken die lengte van SN.
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Hier is die koördinate van S = (-3; 4) en N=(-11; p). Die afstand kan bereken word as: SN=extafstand=extWortel((−11−(−3))2+(p−4)2)=extWortel(82+(p−4)2)
Gegewe dat SN = 10, kan ons die volgende vergelyking opstel: 10=extWortel(64+(p−4)2)
Na kwadrering van beide kante: 100=64+(p−4)2 (p−4)2=36 p−4=6extofp−4=−6 p=10extofp=−2
Step 5
4.5 Indien nog 'n sirkel met middelpunt B(2; 5), radius k direk met middelpunt M raak, bepaal die waarde(s) van k, korrekt tot EEN desimale syfer.
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Answer
Die afstand BM kan bereken word as: BM=extafstand=extWortel((2−(−3))2+(5−4)2)=extWortel(25+1)=extWortel(26)extor5.099
Hieruit volg dat die radius van sirkel B (k) die afstand van BM in mou moet wees. Die waarde van k kan dus bepaal word deur die volgende: k=extafstand−8=5.099−8
Dit gee k = 6.6 units of 9.4 units.