The longer leg of a right triangle is 3 cm longer than the shorter leg.?
The hypotenuse is 6 cm longer than the shorter leg. Find the side lengths of the triangle.
Length of the shorter leg = ? Cm
Length of the longer leg = ? Cm
Length of the hypotenuse = ? Cm
回答 (3)
Let x be the length of the shorter leg
then hypotenuse = x+6
longer leg = x+3
and... the pythagoras theorem
x^2 + (x+3)^2 = (x+6)^2
==> x^2 + x^2 + 6x + 9 - x^2 -12x -36 = 0
==> x^2 -6x -27 = 0
==> x = (6 +/- √(36 + 108))/2 = (6+/-√144)/2 = 18/2 = 9
so.. 9, 12, 15
The longer leg of a right triangle is 3 cm longer than the shorter leg:
Let x = length of shorter leg
Therefore, (x + 3) is the length of the longer leg.
The hypotenuse is 6 cm longer than the shorter leg, so ..
(x + 6) is the hypotenuse.
Now that we have an expression for all three sides, we can put this through Pythagorean Theorem and solve for x:
a² + b² = c²
x² + (x + 3)² = (x + 6)²
simplify each side and put resulting quadratic into standard form:
x² + x² + 6x + 9 = x² + 12x + 36
2x² + 6x + 9 = x² + 12x + 36
x² - 6x - 27 = 0
This factors ...
(x - 9)(x + 3) = 0
x = -3 and 9
We'll throw out the negative number, and we have:
x = 9
So 9 cm is the shortest leg, followed by 12cm, then 15cm for the hypotenuse.
Pythagoras theorem ---> 9 , 12 , 15cm
收錄日期: 2021-04-21 13:25:50
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