What is the area of a triangle with vertices at (0,0), (3,0), and (0,4)?
12
- Step 1: Recognize the triangle type - The points form a right triangle:
Base = segment from (0,0) to (3,0) - length 3.
Height = segment from (0,0) to (0,4) - length 4.
- Step 2: Area formula for a triangle - \[ \text{Area} = \frac{1}{2} \times \text{base} \times \text{height} \]
- Step 3: Substitute values - \[ \text{Area} = \frac{1}{2} \times 3 \times 4 = \frac{12}{2} = 6 \]
- Step 4: Alternate check using determinant formula - \[ \text{Area} = \frac{1}{2} \left| x_1(y_2-y_3) + x_2(y_3-y_1) + x_3(y_1-y_2) \right| \] Substitute $(0,0), (3,0), (0,4)$: \[ = \frac{1}{2} | 0(0-4) + 3(4-0) + 0(0-0) | = \frac{1}{2} | 0 + 12 + 0 | = 6 \]
- Step 5: Conclusion - Area is $6$, matching option (1).
For any natural number $k$, let $a_k = 3^k$. The smallest natural number $m$ for which \[ (a_1)^1 \times (a_2)^2 \times \dots \times (a_{20})^{20} \;<\; a_{21} \times a_{22} \times \dots \times a_{20+m} \] is: