I Need help for this now like a real answer

An objects motion is described by the equation d= 4sin (pi t) what will the height of the object be at 1.75 seconds?

What number should be added to both sides of the equation to complete this square? x^2-10x=7

If the speed of an electromagnetic wave is 100,000 cm/s and its wavelength is 100 cm, what is its frequency? a) 100,000 cycles per second (hz) b) 1 × 10-3 cycles per second (hz) c) 10,000,000 cycles per second (hz) d) 1,000 cycles per second (hz)