1. **Stating the problem:** We are given a right triangle ABC with a right angle at A. Point D lies on segment CB such that AD is perpendicular to CB. The area of triangle ADC is 160 cm². We need to find the area of triangle ADB.
2. **Understanding the figure and given data:**
- Triangle ABC is right-angled at A.
- D lies on CB, dividing it into segments CD = 4k and DB = 3k.
- AD is perpendicular to CB.
- Area of triangle ADC = 160 cm².
3. **Formula for the area of a triangle:**
The area of a triangle is given by
$$\text{Area} = \frac{1}{2} \times \text{base} \times \text{height}$$
4. **Applying the formula to triangles ADC and ADB:**
Since AD is perpendicular to CB, AD is the height for both triangles ADC and ADB, and CD and DB are their respective bases.
5. **Expressing areas in terms of k and AD:**
- Area of triangle ADC:
$$160 = \frac{1}{2} \times 4k \times AD = 2k \times AD$$
- Area of triangle ADB:
$$\text{Area}_{ADB} = \frac{1}{2} \times 3k \times AD = \frac{3}{2} k \times AD$$
6. **Finding AD in terms of k:**
From the first equation:
$$160 = 2k \times AD \implies AD = \frac{160}{2k} = \frac{80}{k}$$
7. **Calculating area of triangle ADB:**
Substitute $AD = \frac{80}{k}$ into the area formula for ADB:
$$\text{Area}_{ADB} = \frac{3}{2} k \times \frac{80}{k} = \frac{3}{2} \times 80 = 120$$
**Final answer:** The area of triangle ADB is **120 cm²**.
Hence, the correct choice is (c) 120.
Triangle Area 7Db2Ad
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