JAMB - Mathematics (2006 - No. 26)
If tan θ = 5/4, find sin2θ - cos2θ.
5/4
41/9
9/41
1
คำอธิบาย
x2 = 52 + 42
= 25 + 16
= 41
x = √41
sin2θ - cos2θ = (5/√41)2 - (4/√41)2
= 25/41 - 16/41
= 9/41
x2 = 52 + 42
= 25 + 16
= 41
x = √41
sin2θ - cos2θ = (5/√41)2 - (4/√41)2
= 25/41 - 16/41
= 9/41