Math Problem Statement

In the figure, PQR is an isosceles triangle and QRT is a straight line. WP is parallel to QR. Find the value of x and y.

Solution

The problem involves an isosceles triangle PQRPQR where QR=PRQR = PR, and a straight line QRTQRT, with a given angle of 140140^\circ at TRT\angle TRT. Line WPWP is parallel to QRQR, and we are asked to find the values of xx and yy, which are the angles PQR\angle PQR and WPQ\angle WPQ, respectively.

Step-by-step solution:

  1. Using angles on a straight line: Since QRTQRT is a straight line, the sum of the angles at point RR must be 180180^\circ. So, for PRT\angle PRT and QRT\angle QRT: x+140=180x + 140^\circ = 180^\circ Solving for xx: x=180140=40x = 180^\circ - 140^\circ = 40^\circ

  2. Using the properties of an isosceles triangle: In triangle PQRPQR, since it is isosceles (QR=PRQR = PR), the base angles are equal. Thus, PQR=PRQ=x=40\angle PQR = \angle PRQ = x = 40^\circ.

  3. Using parallel lines (corresponding angles): Since WPQRWP \parallel QR, the angle yy at point WW is corresponding to PQR\angle PQR, meaning: y=40y = 40^\circ

Thus, the values of xx and yy are both 4040^\circ.

Summary:

  • x=40x = 40^\circ
  • y=40y = 40^\circ

Would you like further details or have any questions?

Related Questions:

  1. How do you calculate angles in a triangle when it is not isosceles?
  2. Why do corresponding angles exist between parallel lines and transversals?
  3. What other methods can be used to find missing angles in geometric problems?
  4. How can exterior angles of a triangle help in solving for unknown angles?
  5. What role do angle properties of straight lines play in other geometry problems?

Tip: Always remember that the sum of angles on a straight line is 180180^\circ, which is useful for finding missing angles.

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Math Problem Analysis

Mathematical Concepts

Isosceles Triangle
Straight Line Angle
Parallel Lines and Corresponding Angles

Formulas

Sum of angles on a straight line = 180°
Base angles of an isosceles triangle are equal

Theorems

Isosceles Triangle Theorem
Corresponding Angles Postulate

Suitable Grade Level

Grades 8-10