Answer:
sin2x = [tex]\frac{4\sqrt{21} }{25}[/tex]
Step-by-step explanation:
Given sinx = [tex]\frac{2}{5}[/tex] = [tex]\frac{opposite}{hypotenuse}[/tex]
Then the third side, the adjacent is found using Pythagoras' identity, that is
adj² + opp² = hyp²
adj² + 2² = 5²
adj² + 4 = 25 ( subtract 4 from both sides )
adj² = 21 ( take the square root of both sides )
adj = [tex]\sqrt{21}[/tex] , then
cosx = [tex]\frac{adj}{hyp}[/tex] = [tex]\frac{\sqrt{21} }{5}[/tex]
Using the double angle identity
sin2x = 2sinxcosx
= 2 × [tex]\frac{2}{5}[/tex] × [tex]\frac{\sqrt{21} }{5}[/tex]
= [tex]\frac{4\sqrt{21} }{25}[/tex]
