D. 10hr. 20 min. :)
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<span>2 real solutions
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Answer:

The answer is 19 - 4, because of PEMDAS.
- Parentheses
- Exponents
- Multiplication
- Division
- Addition
- Subtraction
Any expression wrapped in parentheses always comes first. Whether the sky is pink or blue, parentheses still come first.

Find cos using trig identities:

Therefore

Sub in tan x = 3, (Note that x is in 3rd quadrant, cos x < 0)

Finally, sub into Half-angle formula:(Note x/2 is in 2nd quadrant, tan x<0)