Infatti :
j (b1) = j (cos t) = - sin t = 1(- sin t) + 0(cos t) = 1 c1 + 0 c2
j (b2) = j (sin t) = cos t = 0(- sin t) + 1(cos t) = 0 c1 + 1 c2
quindi
Mb,c(j ) = ,analogamente
j (b1) = j (cos t) = - sin t = 0(cos t) - 1(sin t) = 0 b1 - 1 b2
j (b2) = j (sin t) = cos t = 1(cos t) + 0(sin t) = 1 b1 + 0 b2
quindi
Mb (j ) = .