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Nick
Lv 5
Nick asked in Science & MathematicsMathematics · 10 years ago

Trigonometry: How do I solve for X in the following right triangle?

TriangleABC.

C is a right angle, while the angles of A and B are not given.

AC = X, CB = X+3, and AB = the square root of 17.

How do I solve for X?

4 Answers

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  • 10 years ago
    Favorite Answer

    X^2+(X+3)^2=(sqrt17)^2

    X^2+X^2+6X+9=17

    2X^2+6X-8=0

    x^2+3X-4=0

    (x+4)(x-1)=0

    x=-4............x=1..............cant have a negative side of a triangle

    X=1

  • Anonymous
    10 years ago

    It's a right triangle so you get to use the Pythagorean Theorem for this one

    The sum of the squared sides equals the hypotenuse squared.

    x^2 + (x+3)^2 = 17

    multiply the second term out using FOIL.

    Add like terms.

    Subtract 17 from both sides to set your equation equal to zero.

    Solve for x just like you would with any 2nd degree polynomial. Disregard any negative solutions.

    That is AC's length. Add 3 for CB.

  • 10 years ago

    let's compute using the pythagorean theorem which states that

    ....."the square of the hypotenuse is equal to the sum of the squares of its sides."

    AB is the hypotenuse because it is opposite the right angle.

    ( √ 17 ) ² = x ² + ( x + 3 ) ²

    17 = x ² + x ² + 6x + 9

    .... = 2x ² + 6x + 9

    2x ² + 6x - 8 = 0

    ( 2x + 8 ) ( x - 1 ) = 0

    2x + 8 = 0 ................ & ................ x - 1 = 0

    2x = – 8 ................ & ................ x = 1

    x = – 4 ................ & ................ x = 1

    ............................ x cannot be negative, so;

    x = 1

    ░░░░░

  • Anonymous
    4 years ago

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