The Total solution for NCERT class 6-12
Let ABbe the original height of the tree and broken at C touching the ground at Dsuch thatAC = 5 mand AD = 12 mIn right triangle ∆CAD,AD2 + AC2 =CD2 (By Pythagoras property)⇒ (12)2 + (5)2 =CD2⇒ 144 +25 = CD2⇒ 169 =CD2∴ CD == 13 m
But CD = BCAC + CB = AB5 m + 13 m = AB∴ AB =18 m .Thus, the original height of the tree = 18 m.