Given: ΔABC Prove: The sum of the interior angle measures of ΔABC is 180°.

1. Let points A, B, and C form a

triangle.

given

2. Let be a line passing

through B, parallel to ,

with angles as labeled.

defining a parallel line and labeling angles

3.

4. m∠1 = m∠4, and

m∠3 = m∠5.

Congruent angles have equal measures.

5. m∠4 + m∠2 + m∠5 = 180°

angle addition and definition of a straight angle

6. m∠1 + m∠2 + m∠3 = 180°

substitution

What is the missing step in this proof?
A.
Statement: ∠4 ≅ ∠5, and ∠1 ≅ ∠3.
Reason: Alternate Interior Angles Theorem

B.
Statement: DE is parallel to AC.

Reason: AB is a transversal cutting DE and AC.

C.
Statement: ∠1 ≅ ∠4, and ∠3 ≅ ∠5.

Reason: Alternate Interior Angles Theorem

D.
Statement: ∠1 ≅ ∠4, and ∠3 ≅ ∠5.
Reason: ∠1 and ∠4, and ∠3 and ∠5 are pairs of supplementary angles.

Given: ΔABC

Prove: The sum of the interior angle measures of ΔABC is 180°.

1. Let points A, B, and C form a

triangle.

given

2. Let be a line passing

through B, parallel to ,

with angles as labeled.

defining a parallel line and labeling angles

3.

4. m∠1 = m∠4, and

m∠3 = m∠5.

Congruent angles have equal measures.

5. m∠4 + m∠2 + m∠5 = 180°

angle addition and definition of a straight angle

6. m∠1 + m∠2 + m∠3 = 180°

substitution

What is the missing step in this proof?

A.

Statement: ∠4 ≅ ∠5, and ∠1 ≅ ∠3.

Reason: Alternate Interior Angles Theorem

B.

Statement: DE is parallel to AC.

Reason: AB is a transversal cutting DE and AC.

C.

Statement: ∠1 ≅ ∠4, and ∠3 ≅ ∠5.

Reason: Alternate Interior Angles Theorem

D.

Statement: ∠1 ≅ ∠4, and ∠3 ≅ ∠5.

Reason: ∠1 and ∠4, and ∠3 and ∠5 are pairs of supplementary angles.

Step-by-step explanation:

B.

Statement: DE is parallel to AC.

Reason: AB is a transversal cutting DE and AC.

Step-by-step explanation:

I'm not 100% sure tho, but DE and AC are parallel

.mp4 files, because, video

a net is a diagram that shows a “flattened” view of a solid. in a net, each face and base is shown with all of its dimensions. a net can also serve as a pattern to build a three-dimensional solid.

a pyramid is a three-dimensional object with a base that is a polygon and triangular faces that meet at one vertex.

" the net of a triangular pyramid consists of four triangles. the base here we are given of the pyramid is a equilateral   triangle, and the lateral faces are also triangles "