I need this done asap!

See Below.

Step-by-step explanation:

We want to write a paragraph proof to prove the following theorem:

If ∠N and ∠M are congruent and supplementary, then ∠N and ∠M are right angles.

Each sentence is numbered:

1) Because ∠N and ∠M are congruent, m∠M = m∠N by the definition of congruent angles.

2) Because ∠N and ∠M are supplementary, m∠M + m∠N = 180.

3) Substitute m∠M to m∠N to get m∠M + m∠M = 180, or 2m∠M=180.  

4) The Division Property of Equality then yields m∠M = 90.

5) Substitute m∠N for m∠M to get m∠N = 90.

6) By the definition of right angles, ∠N and ∠M are right angles.

6π units

Step-by-step explanation:

Given::

Radius = 4

Angle measure of partial circle (θ) = 360° - right angle = 360° - 90° = 270°

Arc length = θ/360 × 2πr

Plug in the values

= 270/360 × 2 × π × 4

= 0.75 × 8 × π

= 6π units