Answer:
x ≈ 3.4731
Step-by-step explanation:
∆ACD
∆ACD is a right-angled triangle with AC as the hypotenuse.
According to Pythagoras,
AD² + CD² = AC²
2.25² + CD² = 3²
5.0625 + CD² = 9 Subtract 5.0625 from each side
CD² = 3.9375
∆BCD
∆BCD is a right-angled triangle with BC as the hypotenuse.
BD² + CD² = BC²
x² + 3.9375 = 4²
x² + 3.9375 = 16 Subtract 3.9375 from each side
x² = 12.0625 Take the square root of each side
x ≈ 3.4731
