the sine is positive in both I and II
the cosine is positive in both I and IV
the sine is negative in both III and IV
the cosines is negative in both II and III
so sin A = cos A in only I and III , so your first statement is false.
Repeat the same argument for the 2nd question.
Determine if true or false for each question:
For an angle A in standard position, if sinA = cosA then the terminal arm of the angle lies in quadrant II or IV
For an angle A in standard position, if sinA = -cosA then the terminal arm of the angle lies in quadrant I or III
3 answers
Okay so if I apply that logic to the second statement, the sine will stay the same but the quadrants for the negatives and positives of cosine will swap.
the sine is positive in both I and II
the -cosine is positive in both II and III
the sine is negative in both III and IV
the -cosines is negative in both I and IV
That means sinA = -cosA is only in II and IV, making the second statement also false.
the sine is positive in both I and II
the -cosine is positive in both II and III
the sine is negative in both III and IV
the -cosines is negative in both I and IV
That means sinA = -cosA is only in II and IV, making the second statement also false.
Right