# luas segitiga by clickmath4u

VIEWS: 4,854 PAGES: 5

• pg 1
```									LUAS SEGITIGA
C

7 cm                  75o
4 cm
L ??
A                                        B

http://mediapemb.blogspot.com
Luas segitiga                          = 1/2 alas x tinggi
B

sin C = h/a

c                   a
h = a sin C
h

Luas = 1/2 b x a sin C

A                                                C
b                                        Luas = 1/2 ab sin C

http://mediapemb.blogspot.com
C

b                        a

A                                       B
c

Luas = 1/2 ab sin C
Luas = 1/2 ac sin B
Luas = 1/2 bc sin A
http://mediapemb.blogspot.com
Contoh
C

7 cm                   75o
4 cm
L ??
A                                           B

Luas = 1/2 ab sin C
= 1/2 x 4 x 7 sin 75
= 14 x 0.966 = 13.5 cm2
http://mediapemb.blogspot.com
C

Contoh (lagi)                                     b
4 cm

30o                80o
A                              c          B

a   =     b                       4    =   b
sin A     sin B                   sin 30   sin 80
b = 4 x sin 80 = 7.88 cm
sin 30
C = 180 - A - B = 180 - 30 - 80 = 70o
Luas = 1/2 ab sin C
= 1/2 x 4 x 7.88 x sin 70 = 14.8 cm
http://mediapemb.blogspot.com

```
To top