Respuesta :

Answer:

  • 12. x = 6, side = 83
  • 13. x = 18, side = 29
  • 14. x = 11, sides = 74, 74 and 37
  • 15. x = 23, sides = 95, 95 and 108

Step-by-step explanation:

11 is incomplete, can't solve

12

The triangle is equilateral, so all sides are equal, using one pair to find x:

  • 13x + 5 = 17x - 19
  • 17x - 13x = 5 + 19
  • 4x = 24
  • x = 6

Each side is:

  • 13*6 + 5 = 78 + 5 = 83

13.

Sides are equal as triangle is equilateral

  • QR = 2x - 7
  • RS = 5x - 61
  • QS = x + 11

Finding x by comparing two sides

  • 2x - 7 = 5x - 61
  • 5x - 2x = 61 - 7
  • 3x = 54
  • x = 18

Sides are equal

  • 18 + 11 = 29

14.

Equal sides of isosceles triangle:

  • CD = DE
  • 9x - 25 = 6x + 8
  • 9x - 6x = 8 + 25
  • 3x = 33
  • x = 11

Sides are

  • CD = DE = 9*11 - 25 = 99 - 25 = 74
  • CE = 10*11 - 73 = 110 - 73 = 37

15.

Equal sides of isosceles triangle WXY, WX = WY

  • WX = 4x + 3
  • WY = 7x - 66
  • XY = 5x - 7
  • 4x + 3 = 7x - 66
  • 7x - 4x = 3 + 66
  • 3x = 69
  • x = 23

Sides are:

  • WX=WY = 4*23 + 3 = 95
  • XY = 5*23 - 7 = 108

11. Applying distance formula and finding the sides of DEF, triangle DEF can be classified as an: isosceles triangle.

Applying the definition of equilateral and isosceles triangles, the value of x and the measure of the sides of the given triangles are as follows:

12. x = 6

JK = KL = JL = 83

13. x = 18

QR = RS = QS = 29

14. x = 11

DE = CD = 74

CE = 37

15. x = 23

WY = WX = 95

XY = 108

Recall:

  • All three sides of an equilateral triangle are the same in length.
  • Two sides of an isosceles triangle are equal in length.
  • Distance formula is given as: [tex]d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}[/tex]

11. Given the vertices:

  • D(-2, 3), E(5, 5), F(-4, 10),

Find DE, DF, and EF using [tex]d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}[/tex]

Length of DE:

[tex]DE = \sqrt{(5 -(-2))^2 + (5 - 3)^2} \\\\DE = \sqrt{(7)^2 + (2)^2} \\\\\mathbf{DE = \sqrt{53}}[/tex]

Length of DF:

[tex]DF = \sqrt{(-4 -(-2))^2 + (10 - 3)^2} \\\\DF = \sqrt{(-2)^2 + (7)^2} \\\\\mathbf{DF = \sqrt{53}}[/tex]

Length of EF:

[tex]EF = \sqrt{(-4 -5)^2 + (10 - 5)^2} \\\\EF = \sqrt{(-9)^2 + (5)^2} \\\\\mathbf{EF = \sqrt{106}}[/tex]

Triangle DEF has two equal sides, therefore, it is an isosceles triangle.

12. Given that triangle JKL is equilateral, all it's side will be equal.

Therefore, JK = JL

  • Substitute

[tex]13x + 5 = 8x + 35[/tex]

  • Collect like terms

[tex]13x + 5 = 8x + 35\\\\13x - 8x = -5 + 35\\\\5x = 30\\\\\mathbf{x = 6}[/tex]

Plug in the value of x to find the measure of the sides of triangle JKL.

[tex]JK = 13x + 5 = 13(6) + 5\\\\\mathbf{JK = 83}[/tex]

[tex]KL = 17x - 19 = 17(6) - 19\\\\\mathbf{KL = 83}[/tex]

[tex]JL = 8x + 35 = 8(6) + 35\\\\\mathbf{JL = 83}[/tex]

JK = KL = JL = 83

13. Triangle QRS is equilateral, meaning all its side are equal.

  • [tex]QR = 2x - 7\\\\[/tex]
  • [tex]RS = 5x - 61[/tex]
  • [tex]QS = x + 11[/tex]

To find x, set QR equal to RS (equal sides).

[tex]2x - 7 = 5x - 61[/tex]

  • Collect like terms

[tex]2x - 5x = 7 - 61\\\\-3x = -54\\\\\mathbf{x = 18}[/tex]

Plug in the value of x to find the measure of the sides of triangle QRS.

[tex]QR = 2x - 7 = 2(18) - 7\\\\\mathbf{QR = 29}[/tex]

  • QR = RS = QS = 29 (equal sides)

14. Since CDE is isosceles, therefore, CD = DE.

  • [tex]CD = 9x - 25[/tex]
  • [tex]DE = 6x + 8[/tex]
  • [tex]CE = 10x - 73[/tex]

  • Set CD equal to DE

[tex]9x - 25 = 6x + 8\\\\9x - 6x = 25 + 8\\\\3x = 33\\\\\mathbf{x = 11}[/tex]

Plug in the value of x to find the measure of the sides of triangle CDE.

[tex]CD = 9x - 25 = 9(11) - 25\\\\\mathbf{CD = 74}[/tex]

DE = CD = 74 (congruent sides)

[tex]CE = 10x - 73 = 10(11) - 73\\\\\mathbf{CE = 37}[/tex]

15. We are given that triangle WXY is isosceles, therefore, WX = WY.

  • [tex]WX = 4x + 3[/tex]
  • [tex]XY = 5x - 7[/tex]
  • [tex]WY = 7x - 66[/tex]
  • Set WX equal to WY

[tex]4x + 3 = 7x - 66\\\\4x - 7x = -3 - 66\\\\-3x = -69\\\\\mathbf{x = 23}[/tex]

Plug in the value of x to find the measure of the sides of triangle WXY.

[tex]WX = 4x + 3 = 4(23) + 3\\\\\mathbf{WX = 95}[/tex]

WY = WX = 95 (congruent sides).

[tex]XY = 5x - 7 = 5(23) - 7\\\\\mathbf{XY = 108}[/tex]

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