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#### Online Quiz (WorksheetABCD)

Questions Per Quiz = 2 4 6 8 10

 Example: In a quadrilateral, three angles are 55°, 65° and 105° , Find the fourth angle? Solution: (Ist Method) We know that The sum of the four angles of a quadrilateral is 360°. The sum of the given three angles = 55 + 65+ 105 = 225 The fourth angle = 360 - 225 = 135°. Example: The two angles of a quadrilateral are equal with degree measure 76° and the third angle is given as 120°. Find the fourth angle. Solution: (IInd method) The sum of the angles of a quadrilateral = 360°. Let 'x' be then fourth angle. Therefore 76 + 76 + 120 + x = 360: (Since two of its angles are of 76°). That is 272 + x = 360: Therefore x = 360 - 272 = 88°. Hence the fourth angle is 88°. Example: In a quadrilateral, the third angle is 2 times the fourth and the second angle is 3 times the fourth. The first angle is given as 120°. Find the fourth angle. Solution: Let the fourth angle be 'x'. Here, the third angle = 2 times the fourth angle = 2x. The second angle = 3 times the fourth angle = 3x. We know the sum of the angles of a quadrilateral = 360°. Therefore x + 2x + 3x + 120 = 360. ie 6x + 120 = 360. ie 6x = 360 - 120 = 240. ie x = 240 / 6 = 40. Hence the fourth angle = 40°. Directions: Read the above example carefully and answer the following questions: The sum of the first two angles of a quadrilateral is given by 204°. Also given that the third angle is 3 times the fourth. Find the third and fourth angles. In a quadrilateral, the third angle is 2 times the fourth and the second angle is 3 times the fourth. The first angle is given as 120°. Find the fourth angle.
 Q 1: If, in a quadrilateral, the three angles are 60°, 60° and 90°, then the fourth angle is ________.130°150°140° Q 2: In a quadrilateral, three angles are 50°, 90° and 90°. The fourth angle will be ________.140°130°160° Q 3: In a quadrilateral, three angles are 90°, 80° and 100°. The fourth angle in degree measure will be ________.90°130°100° Q 4: If, in a quadrilateral, three angles are 90°, 90° and 100°, then find its fourth angle. 40°80°90° Question 5: This question is available to subscribers only! Question 6: This question is available to subscribers only!