2b
On the left side, use the measure of each angle.
On the right side, use 180 because the the sum of the measures of the angles of any triangle is always 180.
90 + 45 + <X = 180
135 + <X = 180
<X = 180 - 135
<X = 45
2c
90 + 56 + <H = 180
146 + <H = 180
<H = 180 - 146
<H = 34
3
A right triangle has 1 right angle measuring 90 degrees and two acute angles.
The sum of the measures of the three angles of a triangle is 180.
If you subtract 90 degrees (the right angle's measure) from the total of 180 degrees, 180 - 90 = 90, you get 90 degrees. That means that the sum of the measures of the two acute angles of a right triangle is always 90 degrees.
Circumcenter and circumcirle are shown in the attachment. Assume that the triangle is DEF instead of ABC and that the intersection of perpendiculars is H.
The definition of the circumcenter of a triangle is defined as the point of intersection of all the perpendicular bisectors in the triangle.
The circumcircle passes by all three of the triangle's vertices.
Based on the above, the right choiceS will be:
Point H is the center of the circle that passes through points D, E, and F.
HD = HE
Well, a Centimeter is 10 times bigger than a Milimeter.
So we can convert 9cm by multiplying it by 10
9 × 10= 90mm
SInce we know the length and width of the rectangle, we can now find the area of it, or "the space inside".
Area = length × width
Area = 90mm × 81mm
Area = 7290mm