012.In ABCD, cyclic Quad diagonal intersect at Q. <DBC-70 and <CAB 30,

1.	012.In ABCD, cyclic Quad diagonal intersect at Q. <DBC-70 and <CAB 30, so find -BCD)
Answer» In quadrilateral In aΔCDB andΔBAC, ∠ CDB = ∠ BAC = 30° ...(1) [ Angles in the same segment of a circle are equal ]∠ DBC = 70° ...(2) In Δ BCD, ∠ BCD + ∠ DBC + ∠ CDB = 180° [Sum of all the angles of a triangle is 180°]⇒ ∠ BCD + 70° + 30° = 180° [ from (1) and (2) ] ⇒ ∠ BCD +100° =180° ⇒ ∠ BCD =180° - 100° ⇒ ∠ BCD = 80°

012.In ABCD, cyclic Quad diagonal intersect at Q. <DBC-70 and <CAB 30, so find -BCD)

Answer»

In quadrilateral

In aΔCDB andΔBAC,

∠ CDB = ∠ BAC = 30° ...(1) [ Angles in the same segment of a circle are equal ]∠ DBC = 70° ...(2)

In Δ BCD,

∠ BCD + ∠ DBC + ∠ CDB = 180° [Sum of all the angles of a triangle is 180°]⇒ ∠ BCD + 70° + 30° = 180° [ from (1) and (2) ]

⇒ ∠ BCD +100° =180°

⇒ ∠ BCD =180° - 100°

⇒ ∠ BCD = 80°