Michael J. answered 06/09/16
Tutor
5
(5)
Understanding all Sines of Triangles
Part A)
AB is the hypotenuse
AC and BC are the two legs
Therefore, your equation using Pythagorean theorem is
(AC)2 + (BC)2 = (AB)2
(x - 1)2 + (2x - 5)2 = (2x + 1)2
Expand this equation to get
(x - 1)(x - 1) + (2x - 5)(2x - 5) = (2x + 1)(2x + 1)
(x2 - 2x + 1) + (4x2 - 20x + 25) = 4x2 + 4x + 1
5x2 - 22x + 26 = 4x2 + 4x + 1
Make the left side equal to zero by bringing all terms to the left side.
x2 - 26x + 25 = 0
Part B)
Solve the equation from part A.
We can factor the left side using FOIL.
(x - 25)(x - 1) = 0
Set the factors equal to zero.
x - 25 = 0 and x - 1 = 0
Solve for x from each equation.
x = 25 and x = 1
Part C)
To calculate the area of the triangle, you need to get the actual side measures. Since the algebraic expressions represent the side measures, substitute the accepted value of x into the equation.
x=1 makes AC a side measure a zero value. So we accept x=25.
AC = x - 1
= 25 - 1
= 24 m
BC = 2(25) - 5
= 50 - 5
= 45 m
AB = 2(25) + 1
= 50 + 1
= 51
Checking into the Pythagorean theorem, we get
242+ 452 = 512
576 + 2025 = 2601
2601 = 2601
This checks out. So now we multiply the measures of the legs and divide the result by 2.
Area = (AC * BC) / 2
Plug in the numbers to get the area.
Amy S.
06/09/16