LKS Luas Segitiga

LEMBAR KERJA SISWA (LKS)

Sekolah                           :      SMP

Mata pelajaran              :      Matematika

Kelas/Semester               :      VII/Genap

Materi Pokok                 :      Luas Segitiga

Waktu                             :      8 menit

 

Tujuan Pembelajaran:

1.      Siswa dapat menentukan rumus luas segitiga.

2.      Siswa dapat menghitung luas segitiga.

Langkah-langkah Kegiatan :

1.      Diberikan 3 buah persegipanjang yang kongruen dan 3 jenis segitiga.

2.      Tentukanlah alas dan tinggi pada tiap jenis segitiga yang bersesuaian dengan panjang dan lebar pada persegipanjang, sehingga:

·         alas segitiga (a) sama dengan panjang dari persegipanjang (p)

·         tinggi segitiga (t) sama dengan lebar dari persegipanjang (l)

3.      Bentuklah atau gambarlah setiap jenis segitiga pada masing-masing persegipanjang, kemudian tentukan alas dan tinggi segitiga yang terbentuk pada masing-masing persegipanjang

4.      Dengan menggunakan pendekatan luas persegipanjang, carilah luas segitiga (diskusikan dalam kelompokmu).

Jawab :

                                                                                                                               

                                                                                                                               

                                                                                                                               

                                                                                                                               

                                                                                                                               

                                                                                                                               

                                                                                                                               

                                                                                                                               

                                                                                                                               

                                                                                                                               

                                                                                                                               

                                                                                                                               

                                                                                                                               

                                                                                                                               

                                                                                                                               

                                                                                                                               

                                                                                                                               

Kesimpulan :

                                                                                                                                   

                                                                                                                                   

                                                                                                                                   

                                                                                                                                   

                                                                                                                                   

                                                                                                                                   

                                                                                                                                   

                                                                                                                                   

Kerjakanlah soal di bawah ini!

Diketahui sebuah segitiga memiliki alas = 20 cm dan tinggi = 7 cm. Berapakah luas segitiga tersebut?

                                                                                                                                   

                                                                                                                                   

                                                                                                                                   

                                                                                                                                   

                                                                                                                                   

                                                                                                                                   

                                                                                                                                   

                                                                                                                                   

                                                                                                                                   

                                                                                                                                   

                                                                                                                                   

                                                                                                                                   

Tes

Luas Segitiga

Nama                 :                                                                                                          

No. Absen          :                                                                                                          

Kerjakanlah soal di bawah ini dengan tepat.

1.    Luas sebuah segitiga = 48 cm² dan panjang alasnya = 16 cm.

Hitunglah tinggi segitiga tersebut!

2.    Bu Lala mempunyai kebun jeruk berbentuk segiempat seperti

gambar di bawah. Tentukan luas kebun Bu Lala!