SOLUTION: tan(sin^-1(1/7))

Algebra ->  Trigonometry-basics -> SOLUTION: tan(sin^-1(1/7))      Log On


   



Question 1094706: tan(sin^-1(1/7))
Found 2 solutions by Edwin McCravy, ikleyn:
Answer by Edwin McCravy(20066) About Me  (Show Source):
You can put this solution on YOUR website!


First we look at the inner part: 

That asks for the angle between -pi%2F2 and %22%22+%2B+pi%2F2 whose sine
is 1%2F7.  

Since we know that matrix%281%2C5%2C+sine%2C%22%22=%22%22%2Copposite%2Fhypotenuse%2C%22%22=%22%22%2Cy%2Fr%29,
we draw such an angle by placing a right triangle
in the first quadrant whose angle at the origin is such that its
opposite side is y=1 and its hypotenuse is r=7, like this:



The angle indicated by the red arc is the angle: .

To find the tangent, we must calculate the adjacent side x,
using the Pythagorean theorem:

r%5E2%22%22=%22%22x%5E2%2By%5E2
7%5E2%22%22=%22%22x%5E2%2B1%5E2
49%22%22=%22%22x%5E2%2B1
48%22%22=%22%22x%5E2
sqrt%2848%29%22%22=%22%22x
sqrt%2816%2A3%29%22%22=%22%22x
4sqrt%283%29%22%22=%22%22x

So we now have all three sides of the right triangle:



The problem is 



and since we know that matrix%281%2C5%2C+tangent%2C%22%22=%22%22%2Copposite%2Fadjacent%2C%22%22=%22%22%2Cy%2Fx%29

%22%22=%22%221%2F%284sqrt%283%29%29%22%22=%22%22sqrt%283%29%2F12.

Edwin


Answer by ikleyn(52925) About Me  (Show Source):
You can put this solution on YOUR website!
.
tan(sin^-1(1/7))
~~~~~~~~~~~~~~~~~~~

sin%5E%28-1%29%281%2F7%29  is  arcsin%281%2F7%29.


So,  they want you calculate  tan%28alpha%29,  where alpha%29 = arcsin%281%2F7%29.


Since  alpha%29 = arcsin%281%2F7%29,  it means that  sin%28alpha%29 = 1%2F7.


Then  cos%28alpha%29 = sqrt%281-sin%5E2%28alpha%29%29 = sqrt%281-%281%2F7%29%5E2%29 = sqrt%281-1%2F49%29 = sqrt%28%2849-1%29%2F49%29 = sqrt%2848%29%2F7 = %284%2Asqrt%283%29%29%2F7.


Finally,   tan%28alpha%29 = sin%28alpha%29%2Fcos%28alpha%29 = %28%281%2F7%29%29%2F%28%284%2Asqrt%283%29%29%2F7%29 = 1%2F%284%2Asqrt%283%29%29 = sqrt%283%29%2F12.


For many other similar solved problems, see the lessons
    - Calculating trigonometric functions of angles
    - Advanced problems on calculating trigonometric functions of angles
    - Evaluating trigonometric expressions

    - OVERVIEW of lessons on calculating trig functions and solving trig equations
in this site.