Given the equation [tex]\tan \left(55^{\circ}\right)=\frac{15}{b}[/tex], find the length of [tex]\( b \)[/tex].

A. [tex]3.0 \, \text{cm}[/tex]
B. [tex]9.8 \, \text{cm}[/tex]
C. [tex]10.5 \, \text{cm}[/tex]
D. [tex]12.8 \, \text{cm}[/tex]



Answer :

To find the length of side [tex]\( b \)[/tex] in a right triangle, given the opposite side and the angle, we can use the trigonometric relationship involving the tangent function:

[tex]\[ \tan(\theta) = \frac{\text{opposite}}{\text{adjacent}} \][/tex]

Here, we are given:
- [tex]\(\theta = 55^\circ\)[/tex]
- The length of the opposite side = 15 cm

We need to find the length of the adjacent side [tex]\( b \)[/tex]. Rearranging the tangent formula to solve for [tex]\( b \)[/tex]:

[tex]\[ b = \frac{\text{opposite}}{\tan(\theta)} \][/tex]

Substituting the given values:

[tex]\[ b = \frac{15}{\tan(55^\circ)} \][/tex]

After calculating the above expression, we get [tex]\( b \approx 10.503 \text{ cm} \)[/tex].

Now, let's compare this result to the given options to find the correct answer:
- [tex]\(3.0 \text{ cm}\)[/tex]
- [tex]\(9.8 \text{ cm}\)[/tex]
- [tex]\(10.5 \text{ cm}\)[/tex]
- [tex]\(12.8 \text{ cm}\)[/tex]

The closest option to [tex]\(10.503 \text{ cm}\)[/tex] is [tex]\(10.5 \text{ cm}\)[/tex].

Therefore, the length of side [tex]\( b \)[/tex] is approximately [tex]\( \boxed{10.5 \text{ cm}} \)[/tex].