In the diagram, the length of yz is twice the length of az.

ya is an altitude of δxyz. what is the length of ya?

a) 5 units
b) 10 units
c) 15 units
d) 20 units

This is a 30-60-90 triangle. There is a simple rule to finding the length of each side. The side opposite to the 30 degree angle is regarded as the value "s". In this case, length AZ is considered to be length "s". The side opposite to the right angle is considered to be "2s" and the remaining side length is  Using this, we can find what length "s" is by dividing 10 by 2, which is 5. We multiply this value by the square root of 3 according to the rule, and the final answer is A)