x = sin ( t ) y = sin 2 ( t )
A particle in the x y plane has coordinates that vary with time as shown above. ∣ a ∣ denotes the magnitude of the particle's acceleration. Consider the following ratio:
∣ a ∣ x = 1 ∣ a ∣ x = 0 = B A
If A and B are coprime positive integers, determine A + B .
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This is a parametric equation of y = x 2 on x ∈ [ 1 , 1 ] . So we have y ′ ′ = 2 . And the parametric curve, r ( t ) , is given by r ( t ) = r ′ ′ ( t ) = ⟨ sin ( t ) , sin 2 ( t ) ⟩ ⟨ − sin ( t ) , 2 cos ( 2 t ) ⟩ So we know 2 = 2 cos ( 2 t ) ⇒ t = 0 , 2 π where ∣ r ′ ′ ( t ) ∣ = sin 2 ( t ) + 4 cos 2 ( 2 t ) so ∣ r ′ ′ ( 0 ) ∣ = 2 and ∣ r ′ ′ ( 2 π ) ∣ = 5 . B A = 5 2 ⇒ A + B = 7
X = S i n ( t ) , Y = S i n 2 ( t ) . ⟹ X ′ = C o s ( t ) , Y ′ = S i n ( 2 t ) . ∴ a x = X " = − S i n ( t ) , a y = Y " = 2 C o s ( 2 t ) . ∴ ∣ a ∣ = a x 2 + a y 2 . . . . . . . . . . . . ( A ) W h e n X = 0 , t = 0 . W h e n X = 1 , t = 2 π . S u b s t i t u t i n g i n ( A ) , A = a x 2 + a y 2 = ( − S i n ( 0 ) ) 2 + ( 2 ∗ C o s ( 2 ∗ 0 ) ) 2 , ∴ A = 0 + 4 = 2 . B = ( − S i n ( 2 π ) ) 2 + ( 2 ∗ C o s ( 2 ∗ 2 π ) ) 2 , B = 1 2 + 2 2 = 5 . A + B = 2 + 5 = 7 .
Unable to understand why part of the Latex version also has come up !!!!!
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