solve the obove questions

        for    0°≤x≤360°answer and explanationthe answers are    x = 0°, 30°, 150°, 180°, 360°this can be solved using trigonometric identities.notice that we have a first-power sine term.the terms cos(2x) and cos²x all have some sort of identity that can change them into something with sine. therefore, it will be useful to have everything as sine.the pythagorean identity links cos²x and sin²x via the identity    sin²x + cos²x = 1    ⇒ cos²x = 1 - sin²xthat allows us to convert cosine square into sine squareda cosine double identity to use:       cos(2x) = 1 - 2sin²xnow we can convert everything in terms of sine:     subtracting 1 from both sides results in      get rid of the 2sin²x term on the leftadding 2sin²x to both sides results in    subtracting (1/2)sin x from both sides results in    factor out sin x    we have one side of the equation fully factored and the other side equal to zero.therefore, either sin x = 0 or sin x - 1/2 = 0 because zero times anything is zero (zero factor property). solving the first one    sin x = 0in a unit circle, sine is defined as the ratio of the y-coordinate of the point of intersection of the terminal arm to the radiusby the unit circle, the solutions, for 0°≤ x  ≤ 360°, include 0°, 180°, and 360° (y-coordinate is 0 for those angles)solving the other equation:     sin x - 1/2 = 0move and you get sin x = 1/2. by the unit circle, the solutions include 30° and 150°thus the final solution is    x = 0°, 30°, 150°, 180°, 360°you can test all this in the original equation and all of them will work

10.8109 amu

Step-by-step explanation:

The average atomic mass of boron is determined as the average of the atomic masses of both isotopes weighed by their respective abundances.

Therefore, the average atomic mass is given by:

The average atomic mass of boron isotopes is 10.8109 amu.