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In triangle ABC, the measure of ∠B is 90°, BC=16, and AC=20. Triangle DEF is similar to triangle ABC, where vertices D, E, and F correspond to vertices A, B, and C, respectively, and each side of triangle DEF is 1/3 the length of the corresponding side of triangle ABC. What is the value of sinF?


Sagot :

Answer:

Sin F = 0.6

Step-by-step explanation:

From triangle ABC, applying Pythagoras theorem to determine the length AB;

[tex]/hyp/^{2}[/tex] = [tex]/adj1/^{2}[/tex] + [tex]/adj2/^{2}[/tex]

[tex]/AC/^{2}[/tex] = [tex]/BC/^{2}[/tex] + [tex]/AB/^{2}[/tex]

[tex]/20/^{2}[/tex] = [tex]/16/^{2}[/tex] + [tex]/AB/^{2}[/tex]

400 = 256 + [tex]/AB/^{2}[/tex]

[tex]/AB/^{2}[/tex] = 400 - 256

           = 144

AB = [tex]\sqrt{144}[/tex]

     = 12

AB = 12, AC = 20, BC = 16

Therefore since ΔABC ≅ ΔDEF, and each side of triangle DEF is [tex]\frac{1}{3}[/tex] the length of the corresponding side of triangle ABC.

Then,

DE = [tex]\frac{1}{3}[/tex]AB =  [tex]\frac{1}{3}[/tex] x 12

     = 4

EF =  [tex]\frac{1}{3}[/tex]BC =  [tex]\frac{1}{3}[/tex] x 16

     = [tex]\frac{16}{3}[/tex]

DF =  [tex]\frac{1}{3}[/tex]AC =  [tex]\frac{1}{3}[/tex] x 20

     = [tex]\frac{20}{3}[/tex]

Then, applying trigonometric function to ΔDEF, we have;

Sin F = [tex]\frac{opposite}{hypotenuse}[/tex]

        = [tex]\frac{DE}{DF}[/tex]

        = 4 ÷ [tex]\frac{20}{3}[/tex]

        = 4 x [tex]\frac{3}{20}[/tex]

        = [tex]\frac{3}{5}[/tex]

Sin F = 0.6