Geometry Questions

Multiple choice
  1. $4\sqrt { 3 } units$
  2. $4units$
  3. $\cfrac { 4 }{ \sqrt { 3 } } units$
  4. $2\sqrt { 3 } units$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

By the power of a point theorem, PT^2 = TB * TA. 8^2 = 4 * TA => 64 = 4 * TA => TA = 16. Since TB = 4, AB = 12. AB is a chord. In a circle, if AP is diameter, angle ABP = 90. In triangle ABP, AP^2 = AB^2 + BP^2. Using geometry properties, r = 4*sqrt(3).

Multiple choice
  1. 10 cm

  2. 15 cm

  3. 20 cm

  4. 25 cm

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

Tangents from an external point to a circle are equal. PA = PB = 10. Also, CA = CE and DB = DE. Perimeter of triangle PCD = PC + CD + DP = PC + (CE + ED) + DP = (PC + CA) + (DB + DP) = PA + PB = 10 + 10 = 20.

Multiple choice
  1. $105^{\circ}$
  2. $65^{\circ}$
  3. $95^{\circ}$
  4. $75^{\circ}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The angle between the tangents and the angle between the radii are supplementary. If the tangents are at 75 degrees, the angle between the radii is 180 - 75 = 105 degrees.

Multiple choice
  1. $30^{\circ}$
  2. $120^{\circ}$
  3. $90^{\circ}$
  4. $15^{\circ}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In triangle OAP, angle OAP = 90 degrees. In triangle OAP, angle AOP = 180 - 90 - 30 = 60 degrees. Since triangle OAB is isosceles (OA=OB), angle OAB = (180 - angle AOB)/2. Angle AOB = 2 * angle AOP = 120 degrees. Angle OAB = (180 - 120)/2 = 30 degrees.

Multiple choice
  1. $\displaystyle \left ( \frac{4}{\sqrt{3}} , 2 \sqrt{2} \right )$
  2. $(0, \sqrt{2})$
  3. $(1, 2)$
  4. None of these

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

For a circle x^2 + y^2 = 4, the radius is 2. The angle theta between tangents from (lambda, 0) satisfies sin(theta/2) = r/d = 2/lambda. Given pi/2 < theta < 2pi/3, then pi/4 < theta/2 < pi/3. Thus, sin(pi/4) < 2/lambda < sin(pi/3), which is 1/sqrt(2) < 2/lambda < sqrt(3)/2. Solving for lambda gives 4/sqrt(3) < lambda < 2*sqrt(2).

Multiple choice
  1. True

  2. False

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

In the triangle formed by the center O and the tangents, the angle at the center is 180 - 120 = 60 degrees. Since the triangle OBC is a right triangle at C, the angle BOC is 60 degrees, making it an equilateral triangle or using trigonometry, BC = BO * tan(60). The statement BO = BC is false.

Multiple choice
  1. True

  2. False

  3. Ambiguous

  4. Data Insufficient

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

In triangle ABC, angle BAC = 30. Since AB is diameter, angle ACB = 90. Thus angle ABC = 60. Tangent at C makes angle with chord AC equal to angle in alternate segment, so angle BCD = 30. In triangle BCD, angle CBD = 180 - 60 = 120. Angle BCD = 30, so angle BDC = 180 - 120 - 30 = 30. Since two angles are 30, BC = BD.