Explanation:
6.
the sum of all internal angles in a polygon is
(n-2)×180
n is the number of sides of internal angles.
now, that means that one internal angle of a regular polygon is
(n-2)×180/n
and we know that is 170°.
so,
170 = (n-2)×180/n
170n = 180n - 360
-10n = -360
10n = 360
n = 36
the polygon has 36 sides.
7.
a. is a rectangle or a square, as the fact that all 4 segments of the diagonals are equally long solid to both. after all, a square is just a special rectangle.
but given the picture that suggests different Legrand and widths it is a rectangle.
b.
parallelogram.
the 2 lengths are equal, and the 2 widths are equal. and therefore, both lengths are parallel and both widths are parallel.
but the angles are not 90°. so, it is not a rectangle, but still a parallelogram.
c.
isoceles trapezoid.
top and bottom sides are parallel, but if different size.
the left and right sides are equally long and inclined inwards.
8.
as explained in 7. : the 2 lengths are equal and parallel, and the 2 widths are equal and parallel.
also the diagonals intercept each other at their midpoints. so, both segments of a diagonal are equal.
the sum of all angles is still 360°, and the opposing angles are equal, while every pair of neighboring angles are together 180°.
and - the sum of all angles in a triangle is always 180°.
a. AD = BC = 7
b. DC = AB = 16
c. AC = 2×EC = 2×7 = 14
d. EB = ED = 10.2
angle DAB = angle BCD = 120°
angle ADC = angle ABC = 43 + x
e.
180 = 120 + 43 + x
60 = 43 + x
17° = x
so,
angle ABC = angle ADC = 43 + 17 = 60°
f. angle CDB = x = 17°
g. angle CBD = angle ADB = 43°.
because
180 = CDB + BCD + CBD
180 = 17 + 120 + CBD
43° = angle CBD
h. angle BCD = angle DAB = 120°.