
Yes, if the angle between the two vectors is more than 90o but less than 2700. (cosΘ is negative)

Here, the given equation of parabola is y2= 8x.
The equation of tangent to the parabola y2=8x is,
y= mx + 2/m
This tangent passes through the point (-2, 3)
So, 3 = -2m + 2/m
or, 3m + 2m2 = 2
or, 2m2+3m - 2= 0
or, 2m2 + (4 - 1)m -2 = 0
or, 2m2 + 4m - m - 2 = 0
or, 2m(m + 2) - 1(m+2) = 0
or, (m + 2) (2m - 1) = 0
Either, Or,
m = -2 m = 1/2
Required angle is,

Log2aa=x then, a=(2a)x ......(1)
Log3a2a=y then,2a=(3a)y ......(2)
Log4a 3a=z then, 3a=(4a)z ......(3)
So,
a=(2a)x [from (1)]
Or, a=(3a)xy [from(2)]
Or, a=(4a)xyz [from(3)]
Multiplying both sides by 4a,
4a.a=4a.(4a)xyz
Or,(2a)² =(4a)xyz + 1
Or,(3a)2y =(4a)xyz+1
Or,(4a)2yz =(4a)xyz+1
Or, 2yz = xyz+1 .proved.

Riemann's green is a green pigment ZnO.CoO, which is obtained by heating a mixture of zinc oxide and cobalt nitrate or by the reaction of cobalt nitrate with either or zinc sulphate.

Balance on a bicycle is a matter of constantly correcting against falls, and it's easier when the speed is higher because the inertia of moving forward overcomes the need for corrective actions.

The Rh factor(the Rhesus factor or Rh antigen), is a protein that can be found on the surface of red blood cells. It is one of the most important blood group systems in human blood typing. The presence or absence of the Rh factor is denoted as either Rh-positive (+) or Rh-negative (-).
Fun fact: The Rh factor is named after the Rhesus monkey, in which the protein was first discovered.