Last updated at Dec. 8, 2016 by Teachoo
Example 1 In Fig. , OA = OB and OD = OC. Show that (i) ∆ AOD ≅ ∆ BOC Given: OA = OB and OD = OC To prove: ΔAOD ≅ ΔBOC Proof: Line CD & AB intersect. ∠ AOD = ∠ BOC In ∆ AOD and ∆ BOC, OA = OB ∠ AOD = ∠ BOC OD = OC So, Δ AOD ≅ Δ BOC Example 1 In Fig. , OA = OB and OD = OC. Show that (ii) AD ∥ BC. Δ AOD ≅ Δ BOC ∠ OAD = ∠ OBC But ∠ OAD & ∠ OBC and these form a pair of alternate angles If a transversal intersects two lines such that pair of alternate interior angles is equal, then lines are parallel. Therefore, AD ∥ BC.
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