Find the equation of the line passing through the points (5,21) and (-5,-29) formula: y= a(x) +b

Substitute as followed
y2 = -29
y1 = 21
x2 = -5
x1 = 5
Slope = 

Solve
Slope = 
Slope = 
Slope = 5

So far your equation is
 y = 5x + b
====================================================================
Solve for B ( to solve for B substitute x for -5 and y for -29 in the equation)
B = -4
y = 5x - 4 is your answer

we know that

An isosceles triangle is a triangle that has both two equal sides and two equal angles

In this problem

the triangle RST is an isosceles triangle

so

RS=ST

and

m∠SRT=m∠STR

m∠STR= --------> by supplementary angles

substitute in the formula above

therefore

the answer is