26. September 9, 1981 (9/9/81) was a square-root year date because both the month and the day are square roots of the last two digits of the year.
How many square-root dates will there be during the 21st century?

Step-by-step explanation:

A century has 100 years in it. months only has a max of 31 dates. The following years are perfect squares, 01,04,09,16,25,36,49 64,81,100

It will be 10 square root dates.

<1=121°

m<2=121°

Step-by-step explanation:

Recall that vertical angles are formed whenever two straight lines intersect to form an X-shape.

From the diagram, the measure of <1 is 20x+21 and the measure of <2 is 30x-29.

We know that the measure of two vertical angles are congruent.

Therefore we can write the equation:

We group similar terms to get:

Simplify on both sides to get:

Divide both sides by 10 to get:

The measure of angle 1 is 20(5)+21=100+21=121°

Therefore measure of angle 2 is also121°