Math Problem Statement

In triangle ABC, m∠BAC = 60° and length of the two sides AB and BC are 8 cm and 10 cm respectively. The area of the triangle ABC, in sq. cm, is

Solution

We are given a triangle ABC\triangle ABC with the following information:

  • mBAC=60m\angle BAC = 60^\circ,
  • AB=8cmAB = 8 \, \text{cm},
  • BC=10cmBC = 10 \, \text{cm}.

To find the area of the triangle, we can use the formula for the area of a triangle using two sides and the included angle:

Area=12×AB×BC×sin(BAC)\text{Area} = \frac{1}{2} \times AB \times BC \times \sin(\angle BAC)

Let's plug in the given values:

Area=12×8×10×sin(60)\text{Area} = \frac{1}{2} \times 8 \times 10 \times \sin(60^\circ)

We know that sin(60)=32\sin(60^\circ) = \frac{\sqrt{3}}{2}, so:

Area=12×8×10×32\text{Area} = \frac{1}{2} \times 8 \times 10 \times \frac{\sqrt{3}}{2}

Simplifying:

Area=12×80×32=8034=203cm2\text{Area} = \frac{1}{2} \times 80 \times \frac{\sqrt{3}}{2} = \frac{80\sqrt{3}}{4} = 20\sqrt{3} \, \text{cm}^2

Thus, the area of triangle ABCABC is 203cm220\sqrt{3} \, \text{cm}^2, which is approximately 34.64cm234.64 \, \text{cm}^2.

Would you like more details or have any questions?

Here are some related questions for further exploration:

  1. How would the area change if BAC\angle BAC were 90° instead of 60°?
  2. Can the triangle be classified as scalene, isosceles, or equilateral based on the given information?
  3. What would be the height of the triangle dropped from vertex BB onto side ACAC?
  4. How can you find the length of side ACAC using the Law of Cosines?
  5. What is the perimeter of triangle ABCABC based on this information?

Tip: The sine rule or cosine rule can be used to solve many problems involving non-right triangles.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Geometry
Area of a Triangle

Formulas

Area of a triangle = 1/2 * a * b * sin(θ)
Sine of 60° = √3/2

Theorems

Sine Rule

Suitable Grade Level

Grades 9-11