Step-by-step explanation:
there are 2 similar triangles : ABE and DCE
that means they have the same angles, and the scaling factor from one triangle to the other is the same for every side.
and that means that
DE/AE = EC/BE (= DC/AB)
we know that
AE = AD + DE
BE = BC + EC
a.
so, we have actually
DE/(AD+DE) = EC/(BC+EC)
DE/(10+DE) = 8/(2+8) = 8/10 = 4/5
DE = 4(10+DE)/5
5DE = 4(10+DE) = 40 + 4DE
DE = 40 cm
b.
AD/DE = 3/5
BC/EC must be 3/5 too.
15/EC = 3/5
15 = 3EC/5
75 = 3EC
EC = 25 cm
Answer:
29=b
30=a
Step-by-step explanation:
The formula to use is
n = 360/E
where
n = number of sides
E = measure of exterior angle
In our case, E = 15 so
n = 360/E
n = 360/15
n = 24
This regular polygon has 24 sides
7 x - 5 = 8
7 x = 8 + 5
7 x = 13
x = 13/7
7 ( 13/7) - 5 = 8
91/7 - 35/7 = 56/7
56/7 = 56/7 = 8