Answer:
The answer is "[tex]22^{\circ}[/tex]"
Step-by-step explanation:
Please find the question image file in the attachment:
In this question, [tex]\angle B =90^{\circ}[/tex], that is made up of the two complementary angles that are 57 and 3x.
So, the equation is:
[tex]\to 57+3x=90\\\\\to 3x=90-57\\\\\to 3x= 33\\\\\to x=\frac{33}{3}\\\\\to x= 11[/tex]
In [tex]\Delta ABC[/tex]:
BC=2x
put the value of x in above then [tex]BC= 2\times 11^{\circ} =22^{\circ}[/tex]
