Math Olympiad Geometry: How to Calculate the Area of an Inscribed Circle in a Triangle

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  • Опубликовано: 11 янв 2025

Комментарии • 25

  • @ApexmathematicsInMotion78
    @ApexmathematicsInMotion78  2 месяца назад +5

    R = (a + b - c)/2

    • @paparmar
      @paparmar Месяц назад

      Equivalently, R = a*b /(a+b+c). Easy to remember: radius of inscribed circle in right triangle is twice its area divided by the perimeter.

  • @andrepiotrowski5668
    @andrepiotrowski5668 6 дней назад

    (15, 8, 17) is a primitive Pythagorean tripel. Start with the even side. 8/2 = 1*4 is the only way to build the product with (positive) integers that the first factor is less than the second. Set u := 1, v := 4, t := (v-u) = 3, w := (v+u) = 5.
    Then:
    - a := t * w = 3 * 5 = 15 - The side lengths in terms of t, u, v, w
    - b := 2 * u * v = 2 * 1 * 4 = 8
    - c := t * v + w * u = 3 * 4 + 5 * 1 = 17
    - r_i := t * u = 3 * 1 = 3 - The radius of the inner circle
    - r_c := w * v = 5 * 4 = 20 - The radiusses of the outer circles
    - r_a := t * v = 3 * 4 = 12
    - r_b := w * u = 5 * 1 = 5
    - A = t * u * v * w = 3 * 1 * 4 * 5 = 60 - The area of the triangle in terms of t, u, v, w
    And finally, what we searched for:
    - A_i = π (r_i)² = 9π

  • @aaraaaaaav1
    @aaraaaaaav1 Месяц назад +3

    28.28cm2 approx. U can also make three radii inside the circle by construction and make 3 triangles inside the triangle abc itself. then u can put the whole of triangle abc = sum of 1/2 x 8 x r + 1/2 x 15 x r + 1/2 x 17 x r
    also triangle abc = 1/2 x 8 x 15 which is 60cm2
    now put 60 = 8r/2 + 15r/2 + 17r/2
    to get 60 = 20r
    and r is 3cm
    therefore pir2
    22/7 x 3 x 3 = 28.28cm2 approx

  • @tgarnav5985
    @tgarnav5985 27 дней назад +4

    Simply use r=delta/s

  • @miltonladines4221
    @miltonladines4221 18 часов назад +1

    Poncelet's Theorem:
    The sum of the legs = The sum of hypotenuse + diameter of the inscribed circle
    8 + 15 = 17 + diameter
    23 = 17 + diameter
    23 - 17 = diameter
    6 = diameter
    diameter = 2 (radius)
    6 = 2 ( radius )
    3 = radius
    Area of circle:
    π r² -> π (3)² = 9π
    Sorry for the bad english, it's not my native language

  • @cyruschang1904
    @cyruschang1904 3 месяца назад +3

    17 = (8 - r) + (15 - r) = 23 - 2r
    r = (23 - 17)/2 = 3
    circle area = 9π

  • @rudychan8792
    @rudychan8792 5 дней назад +1

    Simple Way/Formula:
    2s = 8+15+17 = 40 ➡️ s = 20
    A = r•s = (1/2)•8•15 = 60
    r = 60/20 = 3
    O = π•r² = 9π 😉
    Much-much Easier 👍

  • @rey-dq3nx
    @rey-dq3nx 4 дня назад +1

    r²+17r=60
    r²+17r-60=0
    (r+20)(r-3)=0
    r=-20 rejected
    r=3 ok
    Area(circ)=π3²
    =9π

  • @wasimahmad-t6c
    @wasimahmad-t6c 23 дня назад +2

    15-8=7)(15+8=23÷17×7=9.47)(17-9.47÷2=3.63)(8×8-3.63×3.63=50.8231squroth=7.129÷2.4142135624=2.9629×2.9529×3.14159268=27.3942652986 area circile

  • @ManojkantSamal
    @ManojkantSamal Месяц назад +1

  • @LuisdeBritoCamacho
    @LuisdeBritoCamacho 8 дней назад +1

    8 * 15 = 120
    120 / 2 = 60
    8R + 15R + 17R = 120
    40R = 120
    R = 120 / 40
    R = 3
    A (circle) = 9Pi Square Units.

  • @ManojkantSamal
    @ManojkantSamal 6 дней назад +1