find x. A. 21√2 B. 7 C. 21√3 over 2 D. 21√2 over 2

for you to find x you first have to find the adjacent of the 45° angle you can do that by using the other triangle.using the sin ratio

sin60=opposite/hypotenuse

sin60=a/7√3

a=10.5

then after you have found the adjacent you can use the cos ratio

cos45=adjacent/hypotenuse

cos45=10.5/x

cos45x/cos45=10.5/cos45

x=14.849

which is the same as 21√2 over 2

I hope this helps

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jimrgrant1 jimrgrant1 · Answer 2 · 2021-08-02T16:50:02+02:00

Answer:

D

Step-by-step explanation:

Using sine ratio in left right angled triangle to find the altitude a of the large triangle which is common to both right triangles and the exact value

sin60° = [tex]\frac{\sqrt{3} }{2}[/tex] , then

sin60° = [tex]\frac{opposite}{hypotenuse}[/tex] = [tex]\frac{a}{7\sqrt{3} }[/tex] = [tex]\frac{\sqrt{3} }{2}[/tex] ( cross- multiply )

2a = 21 ( divide both sides by 2 )

a = [tex]\frac{21}{2}[/tex]

Using the cosine ratio in the right side triangle and the exact value

cos45° = [tex]\frac{1}{\sqrt{2} }[/tex] , then

cos45° = [tex]\frac{adjacent}{hypotenuse}[/tex] = [tex]\frac{a}{x}[/tex] = [tex]\frac{1}{\sqrt{2} }[/tex] ( cross- multiply )

x = [tex]\sqrt{2}[/tex] a = [tex]\sqrt{2}[/tex] × [tex]\frac{21}{2}[/tex] = [tex]\frac{21\sqrt{2} }{2}[/tex] → D