Solve for [tex]\( c \)[/tex].

Evaluate and simplify:

[tex]\[
\begin{array}{c}
c^2 = 3^2 + 10^2 - 2(3)(10) \cos \left(34^{\circ}\right) \\
c = [?]
\end{array}
\][/tex]

Enter the value of [tex]\( c \)[/tex]. Round to the nearest tenth.



Answer :

Certainly! Let's solve for [tex]\( c \)[/tex] step-by-step using the given values and the Law of Cosines. The Law of Cosines states:

[tex]\[ c^2 = a^2 + b^2 - 2ab \cos(\text{angle}) \][/tex]

Given values are:
- [tex]\( a = 3 \)[/tex]
- [tex]\( b = 10 \)[/tex]
- [tex]\(\text{angle} = 34^\circ \)[/tex]

First, let's calculate the square of each side and the cosine term:

1. Calculate [tex]\( a^2 \)[/tex]:
[tex]\[ a^2 = 3^2 = 9 \][/tex]

2. Calculate [tex]\( b^2 \)[/tex]:
[tex]\[ b^2 = 10^2 = 100 \][/tex]

3. Convert the angle from degrees to radians to use in the cosine function since cosine calculations typically use radians:
[tex]\[ \text{angle in radians} = \frac{34 \pi}{180} \approx 0.5934 \text{ radians} \][/tex]

4. Calculate [tex]\(\cos(\text{angle in radians})\)[/tex]:
[tex]\[ \cos(34^\circ) \approx 0.8290 \][/tex]

5. Calculate the term involving the product of [tex]\( a \)[/tex], [tex]\( b \)[/tex], and [tex]\(\cos(\text{angle})\)[/tex]:
[tex]\[ 2ab \cos(\text{angle}) = 2 \times 3 \times 10 \times 0.8290 = 49.74 \][/tex]

Now, substitute these values into the Law of Cosines formula:

[tex]\[ c^2 = 9 + 100 - 49.74 \][/tex]

Combine the terms to get:

[tex]\[ c^2 = 59.26 \][/tex]

To find [tex]\( c \)[/tex], take the square root of [tex]\( c^2 \)[/tex]:

[tex]\[ c = \sqrt{59.26} \approx 7.698 \][/tex]

Finally, round [tex]\( c \)[/tex] to the nearest tenth:

[tex]\[ c \approx 7.7 \][/tex]

So, the value of side [tex]\( c \)[/tex], rounded to the nearest tenth, is:

[tex]\[ c = 7.7 \][/tex]