Answer:
-4/5
Step-by-step explanation:
Please use a symbol such as x or Ф to represent an angle; your 0 is too easily confused with zero.
If Angle Ф lies in the second quadrant, and sin Ф=3/5, find cos Ф.
The sine of an angle is the ratio of the length of the opposite side to the length of the hypotenuse: sin Ф = opp / hyp = 3 / 5. Thus the opp side has length 3 and the hyp has length 5. By the Pythagorean Theorem,
the adj side has length √(5² - 3²), or √(25-9), or √16, or ±4. Because the angle is in the 2nd quadrant, choose adj = -4.
Then the cosine of this angle is cos Ф = adj / hyp = -4 / 5
