Math Problem Statement

Calculate the length x in the given triangle where angles are 60°, 44°, and the given side is 11 cm.

Solution

To calculate the length xx, we can use the sine rule since we are dealing with a non-right triangle.

The sine rule states: asinA=bsinB=csinC\frac{a}{\sin A} = \frac{b}{\sin B} = \frac{c}{\sin C} Where:

  • a,b,ca, b, c are the sides of the triangle.
  • A,B,CA, B, C are the opposite angles to the respective sides.

Step 1: Identify the given values

  • a=11cma = 11 \, \text{cm} (side opposite the 60° angle).
  • A=60A = 60^\circ (angle opposite side aa).
  • B=44B = 44^\circ (angle opposite xx).

Step 2: Find the third angle CC

The angles of a triangle add up to 180180^\circ. Thus: C=1806044=76C = 180^\circ - 60^\circ - 44^\circ = 76^\circ


Step 3: Apply the sine rule

The sine rule relates the sides and angles: xsin44=11sin60\frac{x}{\sin 44^\circ} = \frac{11}{\sin 60^\circ}

We rearrange to solve for xx: x=11sin44sin60x = \frac{11 \cdot \sin 44^\circ}{\sin 60^\circ}


Step 4: Use a calculator to evaluate the sines

  • sin440.694\sin 44^\circ \approx 0.694
  • sin600.866\sin 60^\circ \approx 0.866

Substitute these values: x=110.6940.866x = \frac{11 \cdot 0.694}{0.866}

x7.6340.8668.8x \approx \frac{7.634}{0.866} \approx 8.8


Final Answer:

The length xx is approximately 8.8 cm (to 2 significant figures).


Let me know if you would like further clarifications! Here are 5 related questions:

  1. How do you derive the sine rule for any triangle?
  2. What is the cosine rule, and when is it used?
  3. How do you find the area of a triangle using sine?
  4. How do you calculate a missing angle in a triangle using the sine rule?
  5. What happens if two angles are the same in a triangle?

Tip: Always check that the angles add up to 180180^\circ before applying trigonometric rules.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Sine Rule
Triangle Properties

Formulas

Sine Rule: a / sin A = b / sin B

Theorems

Triangle Sum Theorem (sum of angles = 180°)
Sine Rule

Suitable Grade Level

Grades 9-11