Math Problem Statement

trouver distance DC

Trouver la distance DC dans le triangle illustré.

Solution

To find the distance DCDC in the given triangle, we can use the Law of Sines. In the triangle ABC\triangle ABC, we are given:

  • AB=91mAB = 91 \, \text{m}
  • BAC=54\angle BAC = 54^\circ
  • ABC=48\angle ABC = 48^\circ

Since the angles in a triangle add up to 180180^\circ, we can find the angle ACB\angle ACB:

ACB=180BACABC=1805448=78\angle ACB = 180^\circ - \angle BAC - \angle ABC = 180^\circ - 54^\circ - 48^\circ = 78^\circ

Now, using the Law of Sines in ABC\triangle ABC, we have:

ABsinACB=ACsinABC=BCsinBAC\frac{AB}{\sin \angle ACB} = \frac{AC}{\sin \angle ABC} = \frac{BC}{\sin \angle BAC}

Thus,

AC=ABsinABCsinACB=91sin48sin78AC = \frac{AB \cdot \sin \angle ABC}{\sin \angle ACB} = \frac{91 \cdot \sin 48^\circ}{\sin 78^\circ}

Calculating ACAC:

  1. sin480.7431\sin 48^\circ \approx 0.7431
  2. sin780.9781\sin 78^\circ \approx 0.9781

AC=91×0.74310.978169.1mAC = \frac{91 \times 0.7431}{0.9781} \approx 69.1 \, \text{m}

Now that we have ACAC, we need more information or additional steps to find DCDC, as it seems to involve additional relationships or right-angle triangles with points DD and CC. Please confirm if there’s any further data on angles or if DD is a particular type of point like the height from CC (forming a right triangle), so I can provide the final calculation for DCDC.

Would you like additional help with these calculations or have specific questions?

Here are five related questions to extend this problem:

  1. What is the significance of point DD in the triangle?
  2. Can we find DCDC if we consider it a line perpendicular to ABAB?
  3. How does knowing DCA\angle DCA or DCB\angle DCB help find DCDC?
  4. If DD represents a height from CC to ABAB, what is the formula for calculating this distance?
  5. How would using the cosine rule change our approach in this scenario?

Tip: For non-right triangles, the Law of Sines and the Law of Cosines are powerful tools to relate sides and angles.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Law of Sines
Angle Sum Property of Triangles

Formulas

Law of Sines: \( \frac{a}{\sin A} = \frac{b}{\sin B} = \frac{c}{\sin C} \)
Angle Sum Property: \( \angle A + \angle B + \angle C = 180^\circ \)

Theorems

Law of Sines
Angle Sum Property of a Triangle

Suitable Grade Level

Grades 10-12