Answer:
The length of segment DC 33 units.
Step-by-step explanation:
Given:
The length of segment BC is 23 units.
To find:
Length of segment DC=?
Solution:
AB = 2x + 7
From the figure ,AB = BC
2x + 7 = 23
2x = 23 - 7
2x = 16
x = 8
In the Δ ABD and ΔCBD
(1) AB = BC(As given in the figure.)
(2) ∠DBA = ∠DBC = 90°
(3) BD = BD(Common side of both the triangle.)
Thus by using SAS congurence property .
Δ ABD ≅ ΔCBD
Thus AD = DC(Corresponding sides of the congurent triangle.)
Thus AD = 4x + 1
Substituting x = 8
AD = 
AD = 32 + 1
AD = 33 unit
Thus AD = DC = 33 unit
16(4) = 64. 7(3) = 21
64/21 simplifies to 3 and 1/21 as 21 goes into 64 three times. Option C is your answer.
The main rule to apply here is:
(i)
![\displaystyle{ a^ {\displaystyle{ (\frac{b}{c})} }= \displaystyle{ \sqrt[c]{a^b}](https://tex.z-dn.net/?f=%5Cdisplaystyle%7B%20a%5E%20%7B%5Cdisplaystyle%7B%20%28%5Cfrac%7Bb%7D%7Bc%7D%29%7D%20%7D%3D%20%5Cdisplaystyle%7B%20%5Csqrt%5Bc%5D%7Ba%5Eb%7D%20)
(ii)If c=2, then we write the following

.
According to these rules:
![\displaystyle{ 5^ {\displaystyle{ (\frac{2}{3})} }= \displaystyle{ \sqrt[3]{5^2}](https://tex.z-dn.net/?f=%5Cdisplaystyle%7B%205%5E%20%7B%5Cdisplaystyle%7B%20%28%5Cfrac%7B2%7D%7B3%7D%29%7D%20%7D%3D%20%5Cdisplaystyle%7B%20%5Csqrt%5B3%5D%7B5%5E2%7D%20)
.

.
![\displaystyle{ 3^ {\displaystyle{ (\frac{2}{5})} }= \displaystyle{ \sqrt[5]{3^2}](https://tex.z-dn.net/?f=%5Cdisplaystyle%7B%203%5E%20%7B%5Cdisplaystyle%7B%20%28%5Cfrac%7B2%7D%7B5%7D%29%7D%20%7D%3D%20%5Cdisplaystyle%7B%20%5Csqrt%5B5%5D%7B3%5E2%7D%20)
.

.