C ) 131 is the answer
in the upside-vertex (not inverted) triangle, angle to your left hand side would be equal to x (as interior alternate angles) = 68
and the angle to the right would be 180-y= 180-117 = 163 (as linear angles)
so the angle at the vertex = 180 - (68 + 163) =49 (as angles in a triangle sum upto 180)
so the angle mz = 180 - 49 = 131 degrees (as linear pair of angles or angle in a straight line)
The first choice,
... a. s(t) = ac[1 + μam cos (2πfmt)] cos (2πfct)
has the carrier frequency cos(2πfct) amplitude modulated by the message signal.
The other expressions represent frequency and phase modulation of various kinds.
number is described as rational if it can be written as a fraction (one integer divided by another integer). A number is irrational if it cannot be written as a fraction. The decimal form of an irrational number does not terminate or recur.
