In ΔDEF Measure of angle E is 90°. If cosD = 513 and DE = 1 cm. Then what is Length of side EF?

Answer: Option B

Solution

Answer: Option B

Solution:

$$\begin{array}{rl}& 5\text{unit}\to 1\text{cm}\\ & 1\text{unit}\to \frac{1}{5}\text{cm}\\ & \text{EF}=2.4\text{cm}\end{array}$$