Math Problem Statement

In ΔHIJ, i = 7.3 inches, h = 6.4 inches and ∠H=57°. Find all possible values of ∠I, to the nearest 10th of a degree.

Solution

We are given a triangle ΔHIJ\Delta HIJ with the following information:

  • Side i=7.3i = 7.3 inches (opposite angle II),
  • Side h=6.4h = 6.4 inches (opposite angle HH),
  • Angle H=57\angle H = 57^\circ.

To find the possible values of I\angle I, we will apply the Law of Sines:

isinI=hsinH\frac{i}{\sin I} = \frac{h}{\sin H}

Step 1: Use the Law of Sines to solve for sinI\sin I

7.3sinI=6.4sin57\frac{7.3}{\sin I} = \frac{6.4}{\sin 57^\circ} First, calculate sin57\sin 57^\circ.

sin570.8387\sin 57^\circ \approx 0.8387

Now, substitute this value into the equation:

7.3sinI=6.40.8387\frac{7.3}{\sin I} = \frac{6.4}{0.8387}

Simplify the right-hand side:

7.3sinI7.63\frac{7.3}{\sin I} \approx 7.63

Now solve for sinI\sin I:

sinI=7.37.630.9567\sin I = \frac{7.3}{7.63} \approx 0.9567

Step 2: Find I\angle I

Using the inverse sine function:

I=sin1(0.9567)73.1I = \sin^{-1}(0.9567) \approx 73.1^\circ

Step 3: Check for another possible value of I\angle I

Since the sine of an angle has two possible values (in the range 00^\circ to 180180^\circ), we check for the supplementary angle: I=18073.1=106.9I' = 180^\circ - 73.1^\circ = 106.9^\circ

Step 4: Validate the second angle

To see if I=106.9I' = 106.9^\circ is valid, recall that the sum of the angles in a triangle must be 180°. If I=106.9I' = 106.9^\circ and H=57\angle H = 57^\circ, the remaining angle JJ would be:

J=180106.957=16.1\angle J = 180^\circ - 106.9^\circ - 57^\circ = 16.1^\circ

This is a valid angle for a triangle, so both 73.173.1^\circ and 106.9106.9^\circ are possible values for I\angle I.

Conclusion:

The possible values of I\angle I are: 73.1 and 106.9\boxed{73.1^\circ \text{ and } 106.9^\circ}

Would you like more details on any of these steps?

Here are five related questions:

  1. How do you apply the Law of Cosines in triangle problems?
  2. How does the Law of Sines handle ambiguous cases (SSA triangles)?
  3. What is the range of the inverse sine function, and why is it important?
  4. How can you check if a triangle is obtuse, acute, or right-angled based on its angles?
  5. How do you use trigonometric identities to solve triangle problems?

Tip: When using the Law of Sines, always check for the second possible angle due to the ambiguity (SSA case).

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Law of Sines
Triangle Properties

Formulas

Law of Sines: (i / sin I) = (h / sin H)
Sum of Angles in a Triangle: ∠H + ∠I + ∠J = 180°

Theorems

Law of Sines

Suitable Grade Level

Grades 10-12