LEARN · EXPLAIN · REVISE

Find the angle in degrees between these nonzero vectors.

Read the idea, work independently, then explain what changed.

TOPIC 01

Plane vectors and applications: mixed assessment

A mixed assessment: identify the method, justify it and revise your reasoning.

Use one hint at a time. A correction explains what changed, not just the final answer.

01 / Foundation#Your turn

\mathbf a=(8,0),\quad\mathbf b=(0,9)

Skills and prerequisite lessons

Working and explanation

BUILD THE REASONING

Hint 1

Use the vector operation law and preserve vector versus scalar types.

Hint 2

A zero dot product gives perpendicular nonzero vectors.

Worked solution

Use the vector operation law and preserve vector versus scalar types.
Calculate or simplify this relation.
$\mathbf a\cdot\mathbf b=0\Rightarrow\cos\theta=0$
Nonzero assumptions are required to define the angle.

The requested value is 90.

Checks and common pitfalls: Nonzero assumptions are required to define the angle.

Think first. Reveal a hint when the class is ready.

Teacher preparation and assessment