This is geometry! Help me please

m<GFC = 149°

Step-by-step explanation:

m<GFC = m<C + m<CDF (exterior angle theorem)

Substitute

12x - 7 = 26 + 8x + 19

Subtract 8x from each side

12x - 7 - 8x = 26 + 8x + 19 - 8x

4x - 7 = 26 + 19

4x - 7 = 45

Add 7 to both sides

4x - 7 + 7 = 45 + 7

4x = 52

Divide both sides by 4

4x/4 = 52/4

x = 13

✔️m<GFC = 12x - 7

Plug in the value of x

m<GFC = 12(13) - 7 = 149°

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

i dont know

step-by-step explanation: