Q. A curve is defined by the parametric equations x(t)=−9cos(4t) and y(t)=−6sin(5t). Find dxdy.Answer:
Find dtdx: To find dxdy for parametric equations, we need to find dtdy and dtdx separately and then divide dtdy by dtdx.
Find dtdy: First, we find dtdx. The derivative of x(t)=−9cos(4t) with respect to t is dtdx=dtd[−9cos(4t)]. Using the chain rule, dtdx=36sin(4t).
Divide for dxdy: Next, we find dtdy. The derivative of y(t)=−6sin(5t) with respect to t is dtdy=dtd[−6sin(5t)].Using the chain rule, dtdy=−30cos(5t).
Simplify dxdy: Now we divide dtdy by dtdx to find dxdy.dxdy=dtdxdtdy=36sin(4t)−30cos(5t).
Simplify dxdy: Now we divide dtdy by dtdx to find dxdy. dxdy=dtdxdtdy=36sin(4t)−30cos(5t).We simplify the expression for dxdy. dxdy=36−30⋅sin(4t)cos(5t)=6−5⋅sin(4t)cos(5t).
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