This follows directly from the double angle identity for cosine and the Pythagorean identity:

So we have

Answer:
I found a pdf that has the lesson overview I just searched up:
Geometry 1e elayn martin gay section 4.1 types of triangles answer sheet
Answer:
4,000,000
Step-by-step explanation:
millions, thousands, hundreds
Being able to do this problem hinges mainly on your knowing the definitions of the trig functions and being able to read side lengths from the given diagram.
csc theta = hypotenuse / opp side = 4 / √(4^2 + 5^2) = 4 / √41.
sin theta is the reciprocal of csc theta, or √41 / 4.
cot theta is adj side / opp side = 5/4.
The value of x is 36.
Solution:
Given angles of a triangle are 2x°, 2x° and x°.
To find the value of x:
<em>Sum of the all the angles of a triangle = 180°</em>
2x° + 2x° + x° = 180°
5x° = 180°
Divide by 5 on both sides of the equation.
x° = 36°
x = 36
The value of x is 36.