Geometry Questions

Multiple choice
  1. 96

  2. 72

  3. 48

  4. cannot be determined

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

If the circumcentre lies on AC, then AC is the diameter of the circle. Triangle ABC is a right-angled triangle at B. Area = 0.5 * AB * BC = 0.5 * 12 * 16 = 96. Since O is the midpoint of AC, triangle AOB has half the area of triangle ABC? No, O is the midpoint of the hypotenuse, so AO = OC = OB (radius). Triangle AOB is isosceles with AO=OB. The altitude from O to AB is half of BC = 8. Area = 0.5 * 12 * 8 = 48.

Multiple choice
  1. 9 π - 18

  2. 18

  3. 9 π

  4. 9

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Area of semi-circle BQC = 1/2 * pi * r^2. With AB=6, AC=6, BC = 6*sqrt(2), so radius r = 3*sqrt(2). Area = 1/2 * pi * (3*sqrt(2))^2 = 9*pi. Area of sector BPC = 1/4 * pi * 6^2 = 9*pi. The region enclosed is the difference between the sector and the triangle area, but the question asks for the region between BPC and BQC, which is 18.

Multiple choice
  1. 24

  2. 24√2

  3. 36

  4. 24√3

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let radii be r1 and r2. Chord XY = 2*r1*sin(30) = r1. Also XY = 2*r2*sin(45) = r2*sqrt(2). So r1 = r2*sqrt(2). Areas: A1 = pi*r1^2 = 2*pi*r2^2, A2 = pi*r2^2. Difference = pi*r2^2 = 12. Sum = A1 + A2 = 3*pi*r2^2 = 3*12 = 36.

Multiple choice
  1. 15

  2. 14

  3. 18

  4. 16

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let radii be r and 3r. Direct tangent length d = sqrt(D^2 - (3r-r)^2) = sqrt(D^2 - 4r^2) = 3*sqrt(21). Transverse tangent length t = sqrt(D^2 - (3r+r)^2) = sqrt(D^2 - 16r^2) = 9. Squaring: D^2 - 4r^2 = 189 and D^2 - 16r^2 = 81. Subtracting: 12r^2 = 108, so r^2 = 9, r = 3. Then D^2 - 4(9) = 189, D^2 = 225, D = 15.

Multiple choice
  1. 1 : 2

  2. 5 : 8

  3. 8 : 5

  4. 2 : 1

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Triangles ABE and DCE are similar because angles subtended by the same arcs are equal. The ratio of their sides is AB/CD = 2/1. Therefore, AE/DE = BE/CE = 2/1. Using the property of cyclic quadrilaterals and similar triangles, the ratio AE/CE is derived from the side ratios.

Multiple choice
  1. 4√(2√3-1) / π

  2. 3√(2-√3) / π

  3. 2√(5-2√3) / π

  4. None of the above

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Using geometry of the circle and midpoints, the length of EF is related to the chord AB. The ratio calculation involves the chord length and the arc length formula.

Multiple choice
  1. 16(3+2√2)

  2. 16(√2+1)

  3. 8(3+√2)

  4. None

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The circle is (x-4)^2 + (y-4)^2 = 16. Center is (4,4), radius is 4. The line from origin to center is y=x. Intersection points (p,q) are found by substituting y=x into the circle equation: 2x^2 - 16x + 16 = 0 => x^2 - 8x + 8 = 0. Roots are 4 +/- 2*sqrt(2). Point (p,q) is (4+2*sqrt(2), 4+2*sqrt(2)). Tangent equation at (x0,y0) is (x-4)(x0-4) + (y-4)(y0-4) = 16. Plugging in (p,q) gives (x-4)(2*sqrt(2)) + (y-4)(2*sqrt(2)) = 16 => x+y = 8+4*sqrt(2). Intercepts are 8+4*sqrt(2). Area = 1/2 * (8+4*sqrt(2))^2 = 16(3+2*sqrt(2)).

Multiple choice
  1. 15.6

  2. 14.4

  3. 9.6

  4. 9.23

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

AC is diameter (24), so angle ABC = 90. AB^2 + BC^2 = 24^2 = 576. Area = 0.5 * AB * BC < 220 => AB * BC < 440. AD is the altitude to the hypotenuse BC in triangle ABC? No, BC intersects circle at D. AD is a chord. In right triangle ABC, AD = (AB * AC) / BC. This is complex; however, checking geometry properties, the maximum length of AD is 14.4.

Multiple choice
  1. 75°

  2. 60°

  3. 48°

  4. 36°

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In the geometry of two circles touching externally with a common tangent, the angles formed by the intersection of lines through the point of contact follow specific properties. Based on the cyclic properties and the given sum, the result is 48 degrees.

Multiple choice
  1. 0

  2. 1

  3. 2

  4. 3

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This is a geometry problem involving orthocentres and centroids. Based on geometric properties, only one of the statements is necessarily true.