129
19
α
1
α
2
α
3
α
4
α
5
2
x
5
x
3
x
120°
20
21
A
B
C
F
E
O
D
c)
x
140°
a
b
30°
a
b
x
25°
145°
x
α α
x
β
β
a
b
140°
50°
x
a
b
a)
b)
d)
nisbati 5:4 kabi. Shu ichki burchaklarini toping.
22*.
19-rasmda tasvirlangan
beshburchak burchaklari
yig‘indisini toping.
23.
20-rasmdagi noma’lum burchaklarni toping.
24.
Ikkita burchagi teng bo‘lgan
uchburchakning teng
yonli ekanini ko‘rsating.
25.
Teng yonli uchburchakning bir burchagi: a) 120°;
b) 70°. Uning qolgan burchaklarini toping.
26.
Teng yonli uchburchakning asosidagi burchaklaridan biri
a) 15°; b) 75° bo‘lsa, qolgan burchaklari nimaga teng?
27.
Ikki uchburchakning barcha mos tomonlari o‘zaro
parallel bo‘lsa, ularning mos burchaklari teng bo‘lishini
isbotlang.
28.
Agar 21-rasmda
AB=BC
,
∠
ABC
=
50°,
AE
va
CF
bissektrisalar bo‘lsa,
AOB
va
EOC
burchaklarni
toping.
29.
22-rasmdagi noma’lum –
x
burchakni toping.
30.
23-rasmdagi noma’lum –
x
burchakni toping.
31.
Ikkita uchburchakning barcha mos tomonlari o‘zaro
perpendikulyar bo‘lsa, ularning mos burchaklari teng
bo‘ladimi? Javobingizni asoslang.
32.
Biror uchburchakni faqat bitta to‘g‘ri chiziq bo‘ylab
qirqib ikkita o‘tkir burchakli
uchburchak hosil qilish
mumkinmi? Javobingizni asoslang.
33.
ABC
uchburchakda
∠
A
+
∠
B
=
110° va
∠
B
+
∠
C
=
100°. Uning ichki burchaklarini toping.
17
138°
18
a)
b)
x
141°
130
22
x
x
a)
d)
e)
f)
g)
b)
c)
x
x
x
x
x
x
23
A
B
C
E
D
x
34.
24-rasmda tasvirlangan stol chirog‘i
shunday yasalganki,
∠
C
=110° va
∠
A
=
∠
B
.
A
va
B
burchaklarning gradus o‘lchovini toping. Nima deb o‘ylaysiz, nega u aynan
shunday shaklda yasalgan?
35.
25-rasmdagi noma’lum burchakni toping.
24
27
a)
b)
c)
d)
e)
f)
j)
h)
k)
l)
