Getal & Ruimte (12e editie) - havo wiskunde B

'Goniometrische vergelijkingen'.

havo wiskunde B 8.4 Goniometrische vergelijkingen

Goniometrische vergelijkingen (7)

opgave 1

Bereken zo mogelijk exact de oplossingen in \([0, 2\pi ]\text{.}\)

3p

a

\(\sin(4t-\frac{1}{3}\pi )=0\)

ExacteWaarde (0)
004f - Goniometrische vergelijkingen - basis - 41ms - dynamic variables

a

De exacte waardencirkel geeft
\(4t-\frac{1}{3}\pi =k⋅\pi \)

1p

\(4t=\frac{1}{3}\pi +k⋅\pi \)
\(t=\frac{1}{12}\pi +k⋅\frac{1}{4}\pi \)

1p

\(t\) in \([0, 2\pi ]\) geeft \(t=\frac{1}{12}\pi ∨t=\frac{1}{3}\pi ∨t=\frac{7}{12}\pi ∨t=\frac{5}{6}\pi ∨t=1\frac{1}{12}\pi ∨t=1\frac{1}{3}\pi ∨t=1\frac{7}{12}\pi ∨t=1\frac{5}{6}\pi \)

1p

4p

b

\(4\cos(\frac{2}{3}\pi x-\frac{3}{4}\pi )=2\)

ExacteWaarde (1)
004g - Goniometrische vergelijkingen - basis - 1ms - dynamic variables

b

Balansmethode geeft \(\cos(\frac{2}{3}\pi x-\frac{3}{4}\pi )=\frac{1}{2}\text{.}\)

1p

De exacte waardencirkel geeft
\(\frac{2}{3}\pi x-\frac{3}{4}\pi =\frac{1}{3}\pi +k⋅2\pi ∨\frac{2}{3}\pi x-\frac{3}{4}\pi =-\frac{1}{3}\pi +k⋅2\pi \)

1p

\(\frac{2}{3}\pi x=1\frac{1}{12}\pi +k⋅2\pi ∨\frac{2}{3}\pi x=\frac{5}{12}\pi +k⋅2\pi \)
\(x=1\frac{5}{8}+k⋅3∨x=\frac{5}{8}+k⋅3\)

1p

\(x\) in \([0, 2\pi ]\) geeft \(x=1\frac{5}{8}∨x=4\frac{5}{8}∨x=\frac{5}{8}∨x=3\frac{5}{8}\)

1p

4p

c

\(-5\sin(3x-\frac{3}{4}\pi )=2\frac{1}{2}\sqrt{2}\)

ExacteWaarde (2)
004h - Goniometrische vergelijkingen - basis - 0ms - dynamic variables

c

Balansmethode geeft \(\sin(3x-\frac{3}{4}\pi )=-\frac{1}{2}\sqrt{2}\text{.}\)

1p

De exacte waardencirkel geeft
\(3x-\frac{3}{4}\pi =1\frac{1}{4}\pi +k⋅2\pi ∨3x-\frac{3}{4}\pi =1\frac{3}{4}\pi +k⋅2\pi \)

1p

\(3x=2\pi +k⋅2\pi ∨3x=2\frac{1}{2}\pi +k⋅2\pi \)
\(x=\frac{2}{3}\pi +k⋅\frac{2}{3}\pi ∨x=\frac{5}{6}\pi +k⋅\frac{2}{3}\pi \)

1p

\(x\) in \([0, 2\pi ]\) geeft \(x=\frac{2}{3}\pi ∨x=0∨x=1\frac{1}{3}\pi ∨x=2\pi ∨x=\frac{5}{6}\pi ∨x=\frac{1}{6}\pi ∨x=1\frac{1}{2}\pi \)

1p

4p

d

\(-2\cos(\frac{2}{5}x+\frac{2}{3}\pi )=\sqrt{3}\)

ExacteWaarde (3)
006x - Goniometrische vergelijkingen - basis - 0ms - dynamic variables

d

Balansmethode geeft \(\cos(\frac{2}{5}x+\frac{2}{3}\pi )=-\frac{1}{2}\sqrt{3}\text{.}\)

1p

De exacte waardencirkel geeft
\(\frac{2}{5}x+\frac{2}{3}\pi =\frac{5}{6}\pi +k⋅2\pi ∨\frac{2}{5}x+\frac{2}{3}\pi =-\frac{5}{6}\pi +k⋅2\pi \)

1p

\(\frac{2}{5}x=\frac{1}{6}\pi +k⋅2\pi ∨\frac{2}{5}x=-1\frac{1}{2}\pi +k⋅2\pi \)
\(x=\frac{5}{12}\pi +k⋅5\pi ∨x=-3\frac{3}{4}\pi +k⋅5\pi \)

1p

\(x\) in \([0, 2\pi ]\) geeft \(x=\frac{5}{12}\pi ∨x=1\frac{1}{4}\pi \)

1p

opgave 2

Bereken zo mogelijk exact de oplossingen in \([0, 2\pi ]\text{.}\)

4p

\(-1+3\sin(3q-\frac{1}{4}\pi )=-4\)

ExacteWaarde (4)
006y - Goniometrische vergelijkingen - basis - 1ms - dynamic variables

Balansmethode geeft \(3\sin(3q-\frac{1}{4}\pi )=-3\) dus \(\sin(3q-\frac{1}{4}\pi )=-1\text{.}\)

1p

De exacte waardencirkel geeft
\(3q-\frac{1}{4}\pi =1\frac{1}{2}\pi +k⋅2\pi \)

1p

\(3q=1\frac{3}{4}\pi +k⋅2\pi \)
\(q=\frac{7}{12}\pi +k⋅\frac{2}{3}\pi \)

1p

\(q\) in \([0, 2\pi ]\) geeft \(q=\frac{7}{12}\pi ∨q=1\frac{1}{4}\pi ∨q=1\frac{11}{12}\pi \)

1p

opgave 3

Los exact op.

3p

a

\(\cos^2(3x+\frac{4}{5}\pi )=1\)

Kwadraat
006z - Goniometrische vergelijkingen - basis - 0ms - dynamic variables

a

\(\cos(3x+\frac{4}{5}\pi )=1∨\cos(3x+\frac{4}{5}\pi )=-1\)

1p

De exacte waardencirkel geeft
\(3x+\frac{4}{5}\pi =k⋅2\pi ∨3x+\frac{4}{5}\pi =\pi +k⋅2\pi \)

1p

\(3x=-\frac{4}{5}\pi +k⋅2\pi ∨3x=\frac{1}{5}\pi +k⋅2\pi \)
\(x=-\frac{4}{15}\pi +k⋅\frac{2}{3}\pi ∨x=\frac{1}{15}\pi +k⋅\frac{2}{3}\pi \)

1p

3p

b

\(\frac{5}{9}\cos(\frac{3}{4}t-\frac{3}{4}\pi )\sin(\frac{2}{3}t+\frac{5}{6}\pi )=0\)

ProductIsNul
0070 - Goniometrische vergelijkingen - basis - 1ms - dynamic variables

b

\(\cos(\frac{3}{4}t-\frac{3}{4}\pi )=0∨\sin(\frac{2}{3}t+\frac{5}{6}\pi )=0\)

1p

De exacte waardencirkel geeft
\(\frac{3}{4}t-\frac{3}{4}\pi =\frac{1}{2}\pi +k⋅\pi ∨\frac{2}{3}t+\frac{5}{6}\pi =k⋅\pi \)

1p

\(\frac{3}{4}t=1\frac{1}{4}\pi +k⋅\pi ∨\frac{2}{3}t=-\frac{5}{6}\pi +k⋅\pi \)
\(t=1\frac{2}{3}\pi +k⋅1\frac{1}{3}\pi ∨t=-1\frac{1}{4}\pi +k⋅1\frac{1}{2}\pi \)

1p

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