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    Escribed Circle of Triangle - Practice Questions & MCQ

    Updated on Sep 18, 2023 18:34 AM

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    • 3 Questions around this concept.

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    In a triangle with sides a,b,c,r_{1}> r_{2}> r_{3}  ( which are the ex-­radii) then:

    Concepts Covered - 1

    Escribed Circle of Triangle

    Escribed Circle of Triangle

    The circle which touches the side BC and two sides AB and AC produced of triangle ABC is called the escribed circle opposite to the angle A. Its radius is denoted by r1. Similarly, r2 and r3 denote the radii of the escribed circles opposite to the angles B and C respectively. 

    Formulae for $r_1, r_2$ and $r_3$
    1. $r_1=\frac{\Delta}{s-a}, r_2=\frac{\Delta}{s-b}, r_3=\frac{\Delta}{s-c}$
    2. $r_1=s \tan \frac{A}{2}, r_2=s \tan \frac{B}{2}, r_3=s \tan \frac{C}{2}$
    3. $r_1=4 R \sin \frac{A}{2} \cos \frac{B}{2} \cos \frac{C}{2}$
    $r_2=4 R \cos \frac{A}{2} \sin \frac{B}{2} \cos \frac{C}{2}$
    $r_3=4 R \cos \frac{A}{2} \cos \frac{B}{2} \sin \frac{C}{2}$

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    Escribed Circle of Triangle

    Mathematics for Joint Entrance Examination JEE (Advanced) : Trigonometry

    Page No. : 5.29

    Line : 45

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