It should be range your welcome
Look carefully at the first pair: (−3, 9), (−3, −5) Note that x does not change, tho' y does. This is how we recognize a vertical line (whose slope is undefined). The equation of this vertical line is x = -3.
Looking at the second pair: from (3,4) to (5,6), x increases by 2 and y by 2; thus, the slope is m = rise/run = 2/2 = 1.
Third pair: as was the case with the first pair, x does not change here, and thus the equation of this (vertical) line is x=0 (which is the y-axis). The slope is undefined.
sin x = cos 54 = sin (90-54) = sin 46
Hence x = 46 deg
Same technique. Sin 21 = cos (5x+9) = sin (90-5x-9)
81-5x = 21
Or 5x = 60
Or x = 12 deg
hope it helps
