CBSE Class 11-science Answered

Above figures show that acute angle θ formed between non-vertical lines AB and CB.

Line AB makes angle α with x-axis and its slope is tanα . If slope of line AB is m_1, then tanα = m₁ .

Line CB makes angle β with x-axis and its slope is tanβ . If slope of line CB is m_2, then tanβ = m₂ .

It can be seen from figure ,  angle θ = angle β - angle α.

..........................(1)

For fig.1 , eqn.(1) can be written as

  ..............................(2)

For fig.2 , eqn.(1) can be written as

  ...........................(3)

In general , eqn.(1) and eqn.(2) are written as