This is a guess, so if it's not right, I completely apologize.
I suppose the answer is C) The 1st angle is a right angle; definition of _|_.
Answer:
Step-by-step explanation:
From the given information:
Note that the possible values of Y are 0 and 1 because;
y = 0 if X = 0 and y = 1 if X = ±1
∴





b)


yeah where are the answer choices? that's the only way we cam help
Answer:
the angle is equal to 60 degree

in case you wonder why we used 105 as LCD,
21 = 3 * 7
15 = 3 * 5
the "3" is common to both denominators, so we "use it once" and our LCD is then 3 * 7 * 5.