Howmany terms of an A.P 9, 17,25,... must be taken to give a sum of 63

1.	Howmany terms of an A.P 9, 17,25,... must be taken to give a sum of 636?38. In the given figure, ABAC. E is a point on CB produced. If AD is perpendicular to BC and EFperpendicular to AC. Prove that "ABD is similar to ÎCEF.
Answer» In ΔABD and ΔCEFAB = AC (Given) ∠ABC = ∠ACB (Equal sides have equal opposite angles) ⇒ ∠ABD = ∠ECF∠ADB = ∠EFC (Each 90°)So, ΔABD ~ ΔECF (AA - Similarity)

Howmany terms of an A.P 9, 17,25,... must be taken to give a sum of 636?38. In the given figure, ABAC. E is a point on CB produced. If AD is perpendicular to BC and EFperpendicular to AC. Prove that "ABD is similar to ÎCEF.

Answer»

In ΔABD and ΔCEFAB = AC (Given)

∠ABC = ∠ACB (Equal sides have equal opposite angles)

⇒ ∠ABD = ∠ECF∠ADB = ∠EFC (Each 90°)So, ΔABD ~ ΔECF (AA - Similarity)