Hello!
To find the base length you use the Pythagorean Theorem

c is the slant height
a is half the base length
b is the height
Put in the values you know

Square the numbers

Add

Take the square root of both sides

Simplify

Hope this helps!
The sum of the interior angles of a polygon is given by
180(n-2)
Where n is the number of sides of the polygon.
Sum = 180(14 - 2)
= 2160°
The answer is C
For each triangle sum of it's angles must add to 180°.
We need to check if these angles satisfy that condition:
32°+51°+97°=180°
They do satisfy. Now we check if any angle has value that is not possible.
32° and 51° angles are OK.
97° angle is also OK. It is obtuse angle.
For each angle measures exactly one triangle exists. In this example we have an obtuse-angle triangle.
Find the least common multiples of 4, 10, 12, 15
multiples of 4:
4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64, 68, 72, 76, 80
multiples of 10: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120
multiples of 12: 12, 24, 36, 48, 60, 72, 84, 96, 108, 120
multiples of 15: 15, 30, 45, 60, 75, 90, 105, 120, 135, 150
The least common multiple of 4, 10, 12, and 15 is 60.
4 x 15 = 60
10 x 6 = 60
12 x 5 = 60
15 x 4 = 60