The area of a triangle is `315 sq. cm.` If the base is 18 cm, find its altitude.

Answer

To find the altitude of the triangle given its area and base, we can follow these steps:

### Step-by-Step Solution:

1. **Write down the formula for the area of a triangle.**
The area \( A \) of a triangle can be calculated using the formula:
\[ A = \frac{1}{2} \times \text{base} \times \text{altitude} \]

2. **Substitute the known values into the formula.**
We know the area \( A = 315 \, \text{sq. cm} \) and the base \( b = 18 \, \text{cm} \). Plugging these values into the formula gives:
\[ 315 = \frac{1}{2} \times 18 \times \text{altitude} \]

3. **Simplify the equation.**
To eliminate the fraction, multiply both sides of the equation by 2:
\[ 2 \times 315 = 18 \times \text{altitude} \]
This simplifies to:
\[ 630 = 18 \times \text{altitude} \]

4. **Solve for the altitude.**
To find the altitude, divide both sides by 18:
\[ \text{altitude} = \frac{630}{18} \]

5. **Calculate the division.**
Performing the division:
\[ \text{altitude} = 35 \, \text{cm} \]

### Final Answer:
The altitude of the triangle is \( 35 \, \text{cm} \).