Cos(A-B) = cosAcosB + sinAsinB
<span>
cos(</span>π/2 - θ) = cos(π/2)cosθ + sin(π/2)sinθ
π/2 = 90°
cos(π/2) = cos90° = 0. sin(π/2) = sin90° = 1
cos(π/2 - θ) = cos(π/2)cosθ + sin(π/2)sin<span>θ
</span>
= 0*cosθ + 1*sin<span>θ = </span>sin<span>θ
Therefore </span>cos(π/2 - θ) = sin<span>θ
QED </span>
Answer:
Midpoint of side EF would be (-.5,4.5)
Step-by-step explanation:
We know that the coordinates of a mid-point C(e,f) of a line segment AB with vertices A(a,b) and B(c,d) is given by:
e=a+c/2,f=b+d/2
Here we have to find the mid-point of side EF.
E(-2,3) i.e. (a,b)=(2,3)
and F(1,6) i.e. (c,d)=(1,6)
Hence, the coordinate of midpoint of EF is:
e=-2+1/2, f=3+6/2
e=-1/2, f=9/2
e=.5, f=4.5
SO, the mid-point would be (-0.5,4.5)
The first one would be x^12
