It seems you have uploaded an image of a math worksheet covering patterns and sequences in Indonesian ("Pola Bilangan"). I will help you solve the questions step-by-step. Let's begin with the breakdown of the questions:

1. Perhatikan gambar konfigurasi berikut ini:

This question shows a pattern of triangles, and the task is to analyze the pattern.

a. Tentukan banyaknya segitiga pada pola ke-10
This question asks you to find the number of triangles in the 10th configuration.

b. Tentukan rumus suku ke-n (Un) konfigurasi dari pola tersebut
Here, you need to find the general formula for the number of triangles in the nth configuration.

2. Diketahui barisan bilangan sebagai berikut: 1, 3, 6, 10, 15, 21, ...

These numbers represent a pattern that you need to analyze.

a. Apakah barisan bilangan tersebut di atas merupakan barisan bilangan aritmatika?
You need to determine if this sequence is arithmetic or not.

3. Diketahui barisan bilangan 36, 33, 30, 27, ...

This sequence is decreasing by a constant amount.

a. Tentukan suku ke-12 barisan bilangan tersebut!
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