Maths with Lemon

Trigonometric Equations

"The two elements the traveler first captures in the big city are extra human architecture and furious rhythm. Geometry and anguish. "

Federico Garcia Lorca

How the unit circle works

What you have to know:

Key Points

  • 1. Watch the video:

How to solve trigonometric equations

What you have to know:

  • The Pythagorean theorem.

Key Points

  • 1. Watch the video:
  • 2. Solving equations with cos x. Watch this video .

Trigonometric identity

What you have to know:

  • The Pythagorean theorem.

Key Points

  • 1. Watch the video:

Area of a triangle

What you have to know:

  • The Pythagorean theorem.

Key Points

  • 1. Watch the video:

Extra

Material and references:

  • Hodder Book SL(ISBN: 9781510462359) :
    18E

Key Points

  • 1. You should be able to solve trigonometric equations graphically and analytically.
    2. To solve \( \sin x = a \):
    let \( x_1 = \sin^{-1} a \),
    then \( x_2 = \pi - x_1 \), and find other solutions by adding or subtracting \( 2\pi \) from \( x_1 \) and \( x_2 \).

  • 2. To solve \( \cos x = a \):
    let \( x_1 = \cos^{-1} a \),
    then \( x_2 = 2\pi - x_1 \), and find other solutions by adding or subtracting \( 2\pi \) from \( x_1 \) and \( x_2 \).

  • 3. To solve \( \tan x = a \):
    let \( x_1 = \tan^{-1} a \),
    and find other solutions by adding or subtracting \( \pi \) from \( x_1 \).

  • 4. You should also be able to solve trigonometric equations that lead to quadratic equations.

IB Past Paper Problems

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