50 points. Please explain each step

Solution given:
Cos[tex]\theta_{1}=\frac{10}{17}[/tex]
[tex]\frac{adjacent}{hypotenuse}=\frac{10}{17}[/tex]
equating corresponding value
we get
adjacent=10
hypotenuse=17
perpendicular=x
now
by using Pythagoras law
Hypotenuse ²=perpendicular²+adjacent ²
substituting value
17²=x²+10²
17²-10²=x²
x²=17²-10²
x²=189
doing square root
[tex]\sqrt{x²}=\sqrt{189}[/tex]
x=[tex]3\sqrt{21}[/tex]
now
In I Quadrant sin angle is positive
Sin[tex]\theta_{1}=\frac{perpendicular}{hypotenuse}[/tex]
Answer:
sin theta = 3 sqrt(21)/17
Step-by-step explanation:
cos theta = adj / hyp
We can find the opp by using the Pythagorean theorem
adj^2 + opp ^2 = hyp^2
10^2 +opp^2 = 17^2
100 + opp^2 = 289
opp^2 = 289-100
opp^2 = 189
Taking the square root
opp = sqrt(189)
opp = 3 sqrt(21)
Since we are in the first quad, opp is positive
sin theta = opp /hyp
sin theta = 3 sqrt(21)/17