Given: ∠ABC is a right angle and ∠DEF is a right angle. Prove: All right angles are congruent by showing that ∠ABC ≅∠DEF.

What are the missing reasons in the steps of the proof?

A flow chart with 4 boxes that are labeled Given, A, B, C from left to right. Box Given contains angle A B C, angle D E F are right angles. Box A contains m angle A B C = 90 degrees and m angle D E F = 90 degrees. Box B contains m angle A B C = m angle D E F. Box C contains angle A B C is-congruent-to angle D E F.

A:

B:

C:

Step-by-step explanation:

A right angle is an angle whose measure is equal to . As the measure of two right angles equals angle on a straight line, while four right angles equal the sum of angles at a point.

Given: <ABC, <DEF are right angles.

The missing reasons in the steps of the proof are:

A: m<ABC = and m<DEF = (Meaning of a right angle)

B: m<ABC = m<DEF (By right angle property)

C: <ABC ≅ <DEF (Congruence property of angles)

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