Maths-
General
Easy

Question

In △ABC, AD⊥BC Also,B D equals 3 C D Prove that 2 A B squared equals 2 A C squared plus B C squared

hintHint:

using pythagoras theorem Find AC squared and AB squared subtract both the equation and substitute given conditions

The correct answer is: Hence proved


    Aim  :- Prove that 2 AB squared equals 2 AC squared plus BC squared
    As BD = 3 CD  ;We get BC = BD +CD = 4 CD
    Applying pythagoras theorem in ΔACD ,We get
    AC squared equals AD squared plus CD squared


    Applying pythagoras theorem in ΔABD ,We get
    AB squared equals BD squared plus AD squared not stretchy rightwards double arrow AD squared equals AB squared minus BD squared  —Eq2
    Substitute Eq2 in Eq1 ,
    AC squared equals AB squared minus BD squared plus CD squared not stretchy rightwards double arrow AC squared equals AB squared plus CD squared minus BD squared
    As BD = 3 CD  ;We get  A C squared equals A B squared plus C D squared minus 9 C D squared
    AC squared equals AB squared minus 8 CD squared not stretchy rightwards double arrow 8 CD squared plus AC squared equals AB squared
    Multiplying with 2 on both sides
    left parenthesis 4 CD right parenthesis squared plus 2 AC squared equals 2 AB squared As BC = 4 CD
    ∴ 2 AB squared equals 2 AC squared plus BC squared
    Hence proved

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