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The perimeter of an isoceles triangle is 16. The length of each of the equal sides is 8-x.?

a)Show that the height (h) of the triangle is 4 . (4-x)^1/2

b)Show that the area of the isosceles triangle A= 4x . (4-x)^1/2

Update:

c) Can you also show what value of x is the area of the triangle maximised. Thanks so much.

2 Answers

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  • 8 years ago
    Favorite Answer

    perimeter of triangle = sum of sides = 16

    an isosceles triangle has two equal sides and they give that each of those is 8 - x

    so the third side = 16 - 2(8 - x)

    = 16 - 16 + 2x

    = 2x

    An altitude (height) of the isosceles triangle divides it in half making 2 right triangles

    the length of the base of each RIGHT triangle is 2x / 2 = x

    Using one of the right triangle and the Pythagorean Theorem:

    (8 - x)² = h² + x²

    h² = (8 - x)² - x²

    h² = 64 - 16x + x² - x²

    h² = 64 - 16x

    h² = 16(4 - x)

    h = √[16(4 - x)]

    h = √16 * √(4 - x)

    h = 4 √(4 - x)

    and that can also be written as h = 4 (4 - x)^(1/2)

    Area of triangle = (1/2) * Base * height

    The base of the isosceles triangle is 2x so:

    Area of triangle = (1/2) * 2x * 4 √(4 - x)

    = 4x √(4 - x)

    and that can also be written as 4x (4 - x)^(1/2)

  • Anonymous
    4 years ago

    Use x because of the fact the fringe of the triangle and six - x because of the fact the fringe of the sq.. subsequently, the portion of the triangle is x/3 and the portion of the sq. is (6-x)/4. as a result, the sum of their aspects is: A(x) = (6-x)² / sixteen + [sqrt (3) / 4]* x²/9 A(x) = (6-x)² / sixteen + [sqrt (3) / 36]* x² A' = (-a million/8)(6-x) + [sqrt (3) / 18] x A' = -3/4 + x/8 + [sqrt (3) / 18] x 0 = -3/4 + x/8 + [sqrt (3) / 18] x 3/4 =x/8 + [sqrt (3) / 18] x 3/4 = x((a million/8 + sqrt (3) / 18 ) 3/4 = x (9 + 4sqrt (3))/seventy two fifty 4/(9 + 4sqrt (3)) = x x= [18(9-4sqrt3)/11] it is approximately 3.6 so because it is your purely serious fee, you are able to attempt if it is a optimal, yet this x fee represents the fringe of the triangle, it is the place you may decrease the twine and use something for the sq.. A(3.6) is the section.

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