Q1 of 35 Page 3

  A quadrilateral has three acute angles, each measures 80°. What is the measure of the fourth angle?            

Sum of the four angles of a quadrilateral = 360°
                80° + 80° + 80° + 4th angle = 360°
... 4th angle = 360° - (80°+80°+80°)=360°-240°=120° 

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2 In a quadrilateral ABCD, the measure of the three angles A, B and C of the quadrilateral are 110°, 70° and 80° respectively. Find the measure of the third angle. 3 In a quadrilateral ABCD, ∠ D is equal to 150° and ∠ A = ∠ B = ∠ C. Find ∠ A, ∠ B and ∠ C. 4 The angles of a quadrilateral are in the ratio 1:2:3:4. What are the measures of the four angles? 5 The In a quadrilateral
(i) which of them have their diagonals bisecting each other?
(ii) which of them have their diagonals perpendicular to each other?
(iii) which of them have equal diagonals ?