Answer:
- [tex]\frac{24}{25}[/tex]
Step-by-step explanation:
Given 630 < A > 720 then A is in the fourth quadrant where
cosA > 0 and sinA < 0
Given
cosA = [tex]\frac{3}{5}[/tex] = [tex]\frac{adjacent}{hypotenuse}[/tex]
Then the triangle is a 3- 4 - 5 with opposite side 4, thus
sinA = - [tex]\frac{opposite}{hypotenuse}[/tex] = - [tex]\frac{4}{5}[/tex]
Using the trigonometric identity
sin2A = 2sinAcosA
= 2 × - [tex]\frac{4}{5}[/tex] × [tex]\frac{3}{5}[/tex]
= [tex]\frac{2(-4)(3)}{5(5)}[/tex] = - [tex]\frac{24}{25}[/tex]
