Answer:
C. 50
Step-by-step explanation:
We are given ΔABC with an altitude BD as shown in the figure.
As it is known that,
'When an altitude is drawn from a right angle of a triangle, then all the three triangles are congruent.'
So, we get that ΔABC ≅ ΔABD ≅ CBD.
Since, the triangles are congruent, their corresponding sides and angles will be congruent.
Moreover, the ratio of the sides will be equal.
So, we get from ΔABC ≅ ΔABD,
[tex]\frac{AD}{AB}=\frac{AB}{AC}[/tex]
i.e. [tex]AD=\frac{AB\times AB}{AC}[/tex]
i.e. [tex]18=\frac{30\times 30}{z}[/tex]
i.e. [tex]18=\frac{900}{z}[/tex]
i.e. [tex]z=\frac{900}{18}[/tex]
i.e. z = 50.
Hence, the value of z is 50.
