ABC and BDC are two triangles as shown in the given figure. If BDC is an isosceles triangle in which BD = DC. Find the value of ∠BDC.
  • a)
    25o
  • b)
    50o
  • c)
    65o
  • d)
    130o
  • e)
    140o
Correct answer is option 'D'. Can you explain this answer?

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Answers

Aditya Joshi
Jan 25, 2019
Since BD = CD,AngleDBC = AngleDCB (Let them be x)
Now three sides of triangles sums up to 180.AngleABC + AngleCBA + AngleCAB = 18040 +40+50+x+x = 180solving this, x = 25.
in triangle DBC,25+25+AngleDBC = 180angleDBC = 130

Since BD = CD,AngleDBC = AngleDCB (Let them be x)Now three sides of triangles sums up to 180.AngleABC + AngleCBA + AngleCAB = 18040 +40+50+x+x = 180solving this, x = 25.in triangle DBC,25+25+AngleDBC = 180angleDBC = 130
Since BD = CD,AngleDBC = AngleDCB (Let them be x)Now three sides of triangles sums up to 180.AngleABC + AngleCBA + AngleCAB = 18040 +40+50+x+x = 180solving this, x = 25.in triangle DBC,25+25+AngleDBC = 180angleDBC = 130