12 multiple-choice questions, progressively harder.
Secants have orders P,A,BP,A,BP,A,B and P,C,DP,C,DP,C,D. The lengths PA,AB,PC,PDPA,AB,PC,PDPA,AB,PC,PD are x,x+6,4,27x,x+6,4,27x,x+6,4,27, respectively. Here xxx itself is a length. Find xxx.
Solution
Correct answer: D
The first whole secant is 2x+6.
Only x=6 is positive. Its external and whole lengths are 6 and 18, with product 108. The other candidate gives negative lengths.
A tangent from PPP has length x+3x+3x+3. A secant has external length xxx and inside chord length 151515. Find the valid xxx.
Correct answer: B
The secant whole is x+15.
The external, whole, and tangent lengths are 1, 16, and 4. They are positive and the product is 16.
Chords have orders A,P,BA,P,BA,P,B and C,P,DC,P,DC,P,D. Their lengths are x+6x+6x+6, 6−x6-x6−x, 555, and 777, respectively. Here xxx is a parameter. Which gives every valid xxx?
Correct answer: C
The chord equation gives
At x=1 the first chord parts are 7 and 5. At x=-1 they are 5 and 7. Both candidates give positive lengths in the inside order. At either 6 or -6, one part is zero and the product is zero.
A circle has radius 131313 and OPOPOP is 555. A chord through PPP has PAPAPA of 999. Find PBPBPB.
Correct answer: A
P is inside. The positive chord product is 144.
An external point has signed power 919191 and center distance 101010. Find the diameter of the circle.
Recover radius squared, then double the radius.
Chord ABABAB has length 141414 and contains interior PPP. Write PA=xPA=xPA=x, so PBPBPB is 14−x14-x14−x. Another chord through PPP has parts 444 and 101010. Which lists every possible PAPAPA?
The product equation is
Both 4 and 10 lie strictly between 0 and 14, so each gives positive parts. Negative values fail both the equation and the length requirement.
Secants have orders P,A,BP,A,BP,A,B and P,C,DP,C,DP,C,D. The lengths PA,PB,PC,CDPA,PB,PC,CDPA,PB,PC,CD are 2,18,3,92,18,3,92,18,3,9. A tangent from PPP touches at TTT. Which pair gives ABABAB and PTPTPT?
AB=16AB=16AB=16
PT=36PT=36PT=36
PT=6PT=6PT=6
AB=18AB=18AB=18
The first inside chord is whole minus external. The second product checks the first.
Both components must be correct.
From △PTA∼△PBT\triangle PTA\sim\triangle PBT△PTA∼△PBT, which proportion directly gives the tangent-secant product for a general configuration?
Read the order P to P, T to B, A to T. Thus PT corresponds to PB, and PA corresponds to PT. The selected proportion cross-multiplies to the tangent square equaling external times whole.
A point PPP is 555 units from the center of a circle and has signed power −50-50−50. Find the radius.
Use the signed definition, keeping its negative value.
This radius exceeds 5, consistent with an interior point.
A diameter lies on a secant ray in order P,A,O,BP,A,O,BP,A,O,B, where OOO is the center. The lengths PA,PBPA,PBPA,PB are 7,197,197,19. Find OPOPOP.
The center is the midpoint of the diameter, hence halfway between the distances to A and B from P.
A secant from external PPP has near and far lengths x+2x+2x+2 and x+9x+9x+9. Its tangent segment has length 2152\sqrt{15}215. Here xxx is a parameter. Find the valid xxx.
The tangent square is 60.
At x=3, the lengths are 5 and 12. At x=-14, the lengths are -12 and -5. Only 3 gives positive lengths in order.
A circle has radius 85\sqrt{85}85. An interior point PPP has center distance 666. An exterior point QQQ has center distance 111111. Which pair gives the positive chord-part product at PPP and a tangent length from QQQ?
Product 494949
Tangent 363636
Tangent 666
Product −49-49−49
For the inside point, subtract its squared center distance from radius squared. For the outside point, reverse that subtraction and take the positive root.
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