The solid angle of a sphere measured from a point in its interior is 4π sr, and the solid angle subtended at the center of a cube by one of its faces is one sixth of that, or 2π 3 sr.

Angle ABC, this angle, is the same as angle DBE.

Statement two, angle 1 is congruent to angle 2, angle 3 is congruent to angle 4.

You start by teaching angles an acute angle, a right angle, an obtuse angle, a straight angle.

And this angle is congruent to angle 1, then angle 1 and angle 2 must be supplementary.

That's angle A, that's angle D.

So we could use angle, angle.

That's one angle here's another angle.

You could say that this angle right here angle AB, angle ABE

This angle plus this angle is going to be equal to this angle.

Or this angle plus this angle plus this angle is equal to 180.

And whether you can spout out, side, angle, side, and angle, side, angle.

And then this angle and this angle.

This angle is equal to this angle.

This angle is different than that angle.

That angle is equal to this angle.

angle ACB is congruent to angle DBC

Angle 1 is congruent to angle 4.

Angle 1 is congruent to angle 3.

That's angle 1 and that's angle 2.

And an acute angle is an angle

The only way that this would be equal to 180, angle 3 plus angle 4, is if angle 4 were a 90 degree angle, and angle 3 were also a 90 degree angle.

Solid

Solid

Solid

Solid

So this angle, this red angle and this brown angle have to be supplements.

This angle down here is a vertical angle, that's gonna be a right angle

Angle

Angle

angle

Angle

Angle

Angle

Angle

Angle?

Let's see, angle X congruent to angle Y.

So angle 2 is congruent to angle 3.

Or angle 1 is congruent to angle 2.

This angle, this whole angle is 180 degrees.

And angle A is congruent to angle D.

So, this is from angle side angle congruency

So, we can employ AAS angle angle side

Angle 1 is a complement of angle 2.

Angle 1 is a supplement of angle 2.