Answer : -3/4 ..............
When I factor[ 2cos (square) - 5cos -3], I get (2cos + 1)(cos - 3). 2cos + 1 = 0, 2cos = -1, cos = -0.5,. Using inv cos on calculator, I get 120 degree related angle.
For any right triangle, we can use the Pythagorean Theorem. The Pythagorean Theorem states that for any right triangle, the legs when squared and added together will be equal to the hypotenuse squared.
In mathematical notation:

Where the variables a and b are the legs and the variable c is the hypotenuse.
Because we know the two side lengths of the triangle, we can solve for the unknown side.
We know the length of one of the legs and the hypotenuse.
Plug in the values.


So, the square root of 476 is the unknown length.
-12,3 ...................................
Given : y = -25 and x = -5
We can notice that if we Multiply 'x' with 5 we get 'y'
That is (-5) × 5 = -25
⇒ x multiplied by 5 = y
(a) The Equation that relates x and y is 5x = y
(b) We found that the Equation of this Direct variation is : 5x = y
The Question is to find the value of y when x = 3
The Value of y at x = 3 can be found by simply substituting x = 3 in the equation we found.
⇒ y = 5x
⇒ y = 5 × 3
⇒ y = 15
So, the Value of y when x = 3 is 15