Math Problem Statement

PS is a diameter of the circle. TRQ and TSP are straight lines. Angle PQR = 108° and angle RTP = 24°. Find angles PRS, QPT, PSR, SRT, and QPR, and give a reason for each statement.

Solution

Let's analyze the given diagram and the corresponding questions:

  1. PS is a diameter of the circle, and as a property of circles, any angle subtended by the diameter at the circumference is a right angle (90°).
  2. TRQ and TSP are straight lines, meaning angles on a straight line add up to 180°.
  3. Given:
    • Angle PQR=108PQR = 108^\circ
    • Angle RTP=24RTP = 24^\circ

(a) We need to find:

1. Angle PRS

  • Since PSPS is the diameter, angle PRSPRS subtended by the diameter at RR will be a right angle: 90(Angle in a semicircle is 90)\boxed{90^\circ} \quad \text{(Angle in a semicircle is } 90^\circ \text{)}

2. Angle QPT

  • Consider the quadrilateral PQRTPQRT formed in the circle. The sum of angles in a cyclic quadrilateral is 180°.
  • In quadrilateral PQRTPQRT, angles PQRPQR and QPTQPT are opposite. Thus, PQR+QPT=180\text{Thus, } PQR + QPT = 180^\circ QPT=180108=72(Opposite angles in a cyclic quadrilateral add up to 180)QPT = 180^\circ - 108^\circ = \boxed{72^\circ} \quad \text{(Opposite angles in a cyclic quadrilateral add up to } 180^\circ \text{)}

3. Angle PSR

  • This angle can be found by considering the fact that the angle RTP=24RTP = 24^\circ, and angles on a straight line add up to 180°. PSR=18024=156(Angles on a straight line add up to 180)PSR = 180^\circ - 24^\circ = \boxed{156^\circ} \quad \text{(Angles on a straight line add up to } 180^\circ\text{)}

4. Angle SRT

  • Angle SRTSRT can be found similarly. Since TRQTRQ is a straight line and the angle RTP=24RTP = 24^\circ, the remaining angle is: SRT=180156=24(Angles on a straight line add up to 180)SRT = 180^\circ - 156^\circ = \boxed{24^\circ} \quad \text{(Angles on a straight line add up to } 180^\circ\text{)}

(b) Find angle QPR.

  • Since angle PQRPQR is 108° and PSPS is the diameter, QPRQPR is the remaining angle in triangle PQRPQR. The sum of angles in a triangle is 180°: QPR=180(PQR+PRS)=180(108+90)=12QPR = 180^\circ - (PQR + PRS) = 180^\circ - (108^\circ + 90^\circ) = \boxed{12^\circ}

Would you like further clarifications or a deeper explanation of any of these steps? Here are five related questions for further practice:

  1. What is the sum of angles in any triangle?
  2. How would you prove that angle PRS is 90° using circle theorems?
  3. If PQR=90PQR = 90^\circ, what would the angle QPTQPT be?
  4. How would the answers change if PQRPQR was less than 108°?
  5. What is the relationship between angles subtended by the same arc in a circle?

Tip: In cyclic quadrilaterals, opposite angles always sum to 180°. This property can help solve many angle problems in circle geometry.

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Math Problem Analysis

Mathematical Concepts

Circle Geometry
Cyclic Quadrilaterals
Angles on a Straight Line

Formulas

Sum of angles in a triangle = 180°
Sum of angles on a straight line = 180°
Opposite angles in a cyclic quadrilateral sum to 180°

Theorems

Angle subtended by a diameter of a circle is 90°
Opposite angles in a cyclic quadrilateral sum to 180°
Angles on a straight line sum to 180°

Suitable Grade Level

Grades 9-11