PLZ HELP QUICKLY, Prove triangle BED is congruent to BEF...need at least 3 reasons

Step-by-step explanation:

1. DE = DF (Def of midpoint)

2. EB = EB (Reflexive)

3. <DEB is congruent to <FEB

3. EB is a transversal- alternate interior angles are congruent

4. SAS

4. SAS theorem states that two triangles are equal if two sides and the angle between those two sides are equal.

10000000000000000000000000000000

the value of v.w= -12.

step-by-step explanation:

we are given three vector r,v and w as:

r = < 5, -5, -2> ; v = < 2, -8, -8> ; w = < -2, 6, -5>

we know that r,v and w could also be represented as:

r=5i-5j-2k

v=2i-8j-8k

and w= -2i+6j-5k

where i,j and k are the unit vectors of x,y and z-axis respectively.

also we know that it has the following property:

i.i=1 ; j.j=1; k.k=1

and i.=j.i=i.k=k.i=j.k=k.j=0

i.e. when we multiply two vectors or we find it's dot product we need to only multiply the components of x coordinates with each other; y with each other and z with each other.

hence, v.w= (2i-8j- -2i+6j-5k)

                  = 2×(-2)+(-8)×(6)+(-8)×(-5)

                  = -4-48+40

                  = -12

hence, v.w= -12