Step-by-step explanation:
Pythagoras, Pythagoras, Pythagoras.
c² = a² + b²
for c being the Hypotenuse (the side opposite of the 90 degree angle).
that is something you should really burn into your brain for life. you will need that many times.
1.
89² = 80² + side²
side² = 89² - 80² = 1521
side = sqrt(1521) = 39 ft
2.
D
because here the x value of 2 has to different assigned result (y) values. but for a function it had to be exactly 1 value.
3.
the longer of the 2 given sides must be the Hypotenuse, because otherwise we would get a negative length.
97² - 72² = side² = 4225
sqrt(4225) = side = 65 cm
4.
the distance between 2 point is the Hypotenuse of a right-angled triangle, with its legs being the differences in x and y coordinates.
F = (-1, 6)
G = (3, 4)
FG² = (-1 - 3)² + (6 - 4)² = 16 + 4 = 20
FG = sqrt(20) = 4.472135955... ≈ 4.5
so, A is the right answer.
5.
that creates a right-angled triangle, with the flag pole and the distance on the floor to the flag pole as the legs, and the rope as Hypotenuse.
rope² = 53² + 28² = 3593
rope = sqrt(3593) ≈ 60 ft
6.
A
85² = 36² + 77²
7225 = 1296 + 5929 = 7225
correct. this is a right-angled triangle.
B
101² = 99² + 20²
10201 = 9801 + 400 = 10201
correct. this is a right-angled triangle.
C
123² = 120² + 27²
15129 = 14400 + 729 = 15129
correct. this is a right-angled triangle.
D
42² = 33² + 24²
1764 = 1089 + 576 = 1665
incorrect.
1764 - 567 = 1089 ?
1197 = 1089
also incorrect.
as is 1764 - 1089 = 567 and 1089 - 567 = 1764
so, this is not a right-angled triangle.
7.
the sum of all angles in a triangle (also in general triangles) is always 180 degrees.
since the right angle is already 90 degrees, it leave only 90 degrees for the other 2 angles.
A is the only correct option. 25 + 65 = 90.
8.
BC = 13
AC = 3
AB² = AC² + BC² = 3² + 13² = 9 + 169 = 178
AB = sqrt(178) = 13.34166406... meter
the tree was then originally
3 + 13.34166406... = 16.34166406... meter high
12.1.1
35² = 21² + side²
side² = 35² - 21² = 1225 - 441 = 784
side = sqrt(784) = 28 m
12.1.2
side² = 16² + 30² = 256 + 900 = 1156
side = sqrt(1156) = 34 ft
12.2.3
61² = 60² + 11²
3721 = 3600 + 121 = 3721
correct. this is a right-angled triangle.
12.2.4
40² = 37² + 9²
1600 = 1369 + 81 = 1450
incorrect. this is not a right-angled triangle.
neither is 1600 - 1369 = 81 nor 1600 - 81 = 1369 nor 1368 - 89 = 1600
12.2.5
38² = 35² + 15²
1444 = 1225 + 225 = 1450
incorrect. this is not a right-angled triangle.
neither is 1444-1225=225 nor 1444-225=1225 nor 1225-225 = 1444
12.2.6
53² = 45² + 28²
2809 = 2025 + 784 = 2809
correct. this is a right-angled triangle.
12.3.8
the x and y coordinate differences between A and B are 6 and 3.
AB² = 6² + 3² = 36 + 9 = 45
AB = sqrt(45) = 6.7
12.3.9
the x and y coordinate differences between B and C are 1 and 7.
BC² = 1² + 7² = 1 + 49 = 50
BC = sqrt(50) = 7.1
12.3.10
the x and y coordinate differences between A and C are 5 and 4.
AC² = 5² + 4² = 25 + 16 = 41
AC = sqrt(41) = 6.4
final question : you need that in many distance calculations, side lengths, diagonals, heights,... for rooms, yards, acres, buildings, mountains, ...