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Given similar, find angles or sides

Chapter 6 Class 10 Triangles

Concept wise

Last updated at May 29, 2018 by Teachoo

Ex 6.3, 2 In figure, ΔODC ∼ ΔOBA, ∠BOC = 125° and ∠CDO = 70°. Find ∠DOC, ∠DCO and ∠OAB. Given: Δ ODC ∼ Δ OBA ∠ BOC = 125° ∠ CDO = 70° To find: ∠DOC, ∠DCO and ∠OAB Solution: Here, BD is a line, So, we can apply linear pair on it. ∠BOC + ∠DOC = 180° 125° + ∠DOC = 180° ∠DOC = 180° – 125° ∠DOC = 180° – 125° ∠DOC = 55° Now in Δ DCO ∠CDO + ∠DCO + ∠DOC = 180° 70° + ∠DCO + 55° = 180° 125° + ∠DCO = 180° ∠DCO = 180° - 125° ∠DCO = 55° Now it is given that ΔODC ∼ ΔOBA Hence ∠DCO = ∠OAB 55° = ∠ OAB ∠OAB = 55°