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solve for the unknown parts of the triangle (i asked this question earlier but decided to up the pts hoping someone would answer T---T)

solve for the unknown parts of the triangle (i asked this question earlier but decided-example-1
User Vahdet
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2 Answers

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Answer: 1: ∠L = 53, LA = 23.15 ft, BA = 18.9 ft, 2: ∠S = 57.31, WS = 69.36 cm, SA = 58.37 cm, 3: AB = 19.33 cm, ∠B = 30.71 ,∠C = 99.29

Explanation:

For triangle 1, solving for the missing angle is quite simple since all internal angles of a triangle add up to 180, so 180 - 102 - 25 = 53. For triangles that aren't right-angle triangles, the first thing we want to do is add a line segment that bisects an angle and is perpendicular to one side. This will separate the triangle into two right-angle triangles and allow us to use Sin, Cos, and Tan to find missing angles and sides. In the case of traingle 1, I split line segment LA creating angle "C" (random letter). For the triangle LBC, I needed to find LC, so using Cosθ = Adjacent/Hypotenuse, I got Cos(53) = x/10 = 6.02. Before solving for BA and AC I need to find the side length of LB -> Tanθ = Opposite/Adjacent -> Tan(53) = x/6.02 -> x = 7.99. Now I can solve for BA and CA: BA -> Sin(25) = 7.99/x -> x = 18.9, CA -> Tan(25) = 7.99/x = 17.13. Now I have all my angles and sides besides LA which is just adding LC and AC -> 6.02 + 17.13 = 23.15.

Triangle 2, same process: ∠S = 180 - 79 - 43.69 = 57.31

SA = SB + BA -> WB: Sin(43.69) = x/84.5 = 58.37

AB: Tan(43.69) = 58.37/x = 61.1

BS: Tan(57.31) = 58.37/x = 37.45

WS: Sin(57.31) = 58.37/x = 69.36

AS: AB + BS = 98.55

Triangle 3, similar process, just involves finding an extra angle:

AB = AT + TB -> CT: Sin(50) = x/10 = 7.66

∠ACT: Cos^-1(7.66/10) = 40

AT: Cos(50) = x/10 = 6.43

∠BCT: Cos^-1(7.66/15) = 59.29

∠B: sin^-1(7.66/15) = 30.71

BT: Tan(30.71) = 7.66/x = 12.9

AB: AT + BT = 6.43 + 12.9 = 19.33

∠C = ∠BCT + ∠ACT = 40 + 59.29 = 99.29

I hope this helps! I am greatly sorry if something doesn't add up or make sense, and will fix it if need be just lmk! (Image is example of line segment)

solve for the unknown parts of the triangle (i asked this question earlier but decided-example-1
User Shridharama
by
8.1k points
3 votes

Answer:

1) ∠L = 53°

AL = 23.14 ft

AB = 18.90 ft

2) ∠S = 53.71°

SW = 69.35 cm

AS = 98.56 cm

3) ∠B = 30.71°

∠C = 99.29°

AB = 19.32 cm

Explanation:

To solve for the unknown parts of the triangles, we can use the Angle Sum Property of a Triangle and the Sine Rule.

The Angle Sum Property of a Triangle states that the interior angles of a triangle always sum to 180°.


\boxed{\begin{minipage}{7.6 cm}\underline{Sine Rule} \\\\$(a)/(\sin A)=(b)/(\sin B)=(c)/(\sin C)$\\\\\\where:\\ \phantom{ww}$\bullet$ $A, B$ and $C$ are the angles. \\ \phantom{ww}$\bullet$ $a, b$ and $c$ are the sides opposite the angles.\\\end{minipage}}

Question 1

Given values of triangle ABL:

  • A = 25°
  • B = 102°
  • LN = 10 ft

As we have been given two angles, we can use the Angle Sum Property of a Triangle to find the measure of the third angle, ∠L.


\angle A + \angle B + \angle L = 180^(\circ)


25^(\circ) + 102^(\circ) + \angle L = 180^(\circ)


127^(\circ) + \angle L = 180^(\circ)


\angle L = 53^(\circ)

To find the lengths of sides AB and AL, use the Sine Rule.


(LN)/(\sin A)=(AL)/(\sin B)=(AB)/(\sin L)


(10)/(\sin 25^(\circ))=(AL)/(\sin 102^(\circ))=(AB)/(\sin 53^(\circ))

Therefore:


AL=(10\sin 102^(\circ))/(\sin 25^(\circ))=23.1449440...=23.14\sf \; ft


AB=(10\sin 53^(\circ))/(\sin 25^(\circ))=18.8973260...=18.90\; \sf ft


\hrulefill

Question 2

Given values of triangle ASW:

  • A = 43.69°
  • W = 79°
  • AW = 84.5 cm

As we have been given two angles, we can use the Angle Sum Property of a Triangle to find the measure of the third angle, ∠S.


\angle A + \angle S + \angle W = 180^(\circ)


43.69^(\circ) + \angle S+79^(\circ) = 180^(\circ)


122.69^(\circ) + \angle S= 180^(\circ)


\angle S = 57.31^(\circ)

To find the lengths of sides AS and SW, use the Sine Rule.


(SW)/(\sin A)=(AW)/(\sin S)=(AS)/(\sin W)


(SW)/(\sin 43.69^(\circ))=(84.5)/(\sin 57.31^(\circ))=(AS)/(\sin 79^(\circ))

Therefore:


SW=(84.5\sin 43.69^(\circ))/(\sin 57.31^(\circ))=69.3542652...=69.35\; \sf cm


AS=(84.5\sin 79^(\circ))/(\sin 57.31^(\circ))=98.5586958...=98.56\; \sf cm


\hrulefill

Question 3

Given values of triangle ABC:

  • A = 50°
  • BC = 15 cm
  • AC = 10 cm

To find angle B, use the Sine Rule.


(BC)/(\sin A)=(AC)/(\sin B)=(AB)/(\sin C)


(15)/(\sin 50^(\circ))=(10)/(\sin B)=(AB)/(\sin C)


\sin B=(10\sin 50^(\circ))/(15)


B=\sin^(-1)\left((10\sin 50^(\circ))/(15)\right)=30.7102207...^(\circ)=30.71^(\circ)

As we now have two angles, we can use the Angle Sum Property of a Triangle to find the measure of the third angle, ∠C.


\angle A + \angle B + \angle C = 180^(\circ)


50^(\circ) + 30.71^(\circ) +\angle C= 180^(\circ)


80.71^(\circ) + \angle C= 180^(\circ)


\angle C = 99.29^(\circ)

To find the length of the third side, AB, use the Sine Rule.


(BC)/(\sin A)=(AC)/(\sin B)=(AB)/(\sin C)


(15)/(\sin 50^(\circ))=(10)/(\sin 30.71^(\circ))=(AB)/(\sin 99.29^(\circ))


AB=(15\sin 99.29^(\circ))/(\sin 50^(\circ))=19.3242...=19.32\;\sf cm

User Steve Wong
by
8.8k points

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