At Westonci.ca, we provide reliable answers to your questions from a community of experts. Start exploring today! Discover a wealth of knowledge from experts across different disciplines on our comprehensive Q&A platform. Get immediate and reliable solutions to your questions from a community of experienced professionals on our platform.

(a) If [tex][tex]$\cos 30^{\circ} = \frac{\sqrt{3}}{2}$[/tex][/tex], find the values of [tex][tex]$\sin 15^{\circ}$[/tex][/tex], [tex][tex]$\cos 15^{\circ}$[/tex][/tex], and [tex][tex]$\tan 15^{\circ}$[/tex][/tex].

Sagot :

To find the values of [tex]$\sin 15^{\circ}$[/tex], [tex]$\cos 15^{\circ}$[/tex], and [tex]$\tan 15^{\circ}$[/tex], we can use the half-angle formulas. Given that [tex]$\cos 30^{\circ} = \frac{\sqrt{3}}{2}$[/tex], we'll follow these steps:

### Step 1: Calculate [tex]$\sin 15^{\circ}$[/tex]
We use the half-angle formula for sine, which states:
[tex]\[ \sin \left(\frac{\theta}{2}\right) = \sqrt{\frac{1 - \cos \theta}{2}} \][/tex]
Here, [tex]$\theta = 30^{\circ}$[/tex], so we have:
[tex]\[ \sin 15^{\circ} = \sin \left(\frac{30^{\circ}}{2}\right) = \sqrt{\frac{1 - \cos 30^{\circ}}{2}} \][/tex]
Substituting the given value of [tex]$\cos 30^{\circ}$[/tex]:
[tex]\[ \sin 15^{\circ} = \sqrt{\frac{1 - \frac{\sqrt{3}}{2}}{2}} \][/tex]
Calculating inside the square root:
[tex]\[ \sin 15^{\circ} = \sqrt{\frac{2/2 - \sqrt{3}/2}{2}} = \sqrt{\frac{2 - \sqrt{3}}{4}} = \sqrt{\frac{2 - \sqrt{3}}{4}} \][/tex]
Taking the square root:
[tex]\[ \sin 15^{\circ} \approx 0.2588 \][/tex]

### Step 2: Calculate [tex]$\cos 15^{\circ}$[/tex]
We use the half-angle formula for cosine, which states:
[tex]\[ \cos \left(\frac{\theta}{2}\right) = \sqrt{\frac{1 + \cos \theta}{2}} \][/tex]
Again, with [tex]$\theta = 30^{\circ}$[/tex]:
[tex]\[ \cos 15^{\circ} = \cos \left(\frac{30^{\circ}}{2}\right) = \sqrt{\frac{1 + \cos 30^{\circ}}{2}} \][/tex]
Substituting the given value of [tex]$\cos 30^{\circ}$[/tex]:
[tex]\[ \cos 15^{\circ} = \sqrt{\frac{1 + \frac{\sqrt{3}}{2}}{2}} \][/tex]
Calculating inside the square root:
[tex]\[ \cos 15^{\circ} = \sqrt{\frac{2/2 + \sqrt{3}/2}{2}} = \sqrt{\frac{2 + \sqrt{3}}{4}} \][/tex]
Taking the square root:
[tex]\[ \cos 15^{\circ} \approx 0.9659 \][/tex]

### Step 3: Calculate [tex]$\tan 15^{\circ}$[/tex]
The tangent of an angle is the ratio of the sine of that angle to the cosine of that angle:
[tex]\[ \tan \theta = \frac{\sin \theta}{\cos \theta} \][/tex]
Thus,
[tex]\[ \tan 15^{\circ} = \frac{\sin 15^{\circ}}{\cos 15^{\circ}} \][/tex]
Substituting the approximated values:
[tex]\[ \tan 15^{\circ} = \frac{0.2588}{0.9659} \][/tex]
Calculating the ratio:
[tex]\[ \tan 15^{\circ} \approx 0.2679 \][/tex]

### Summary
Thus, the values are approximately:
[tex]\[ \sin 15^{\circ} \approx 0.2588, \quad \cos 15^{\circ} \approx 0.9659, \quad \tan 15^{\circ} \approx 0.2679 \][/tex]
Thank you for trusting us with your questions. We're here to help you find accurate answers quickly and efficiently. We appreciate your visit. Our platform is always here to offer accurate and reliable answers. Return anytime. Westonci.ca is your go-to source for reliable answers. Return soon for more expert insights.