Question

what is $m\angle cbd$?
triangle diagram with points a, d, c on a line, b above. angles: $\angle a = 60^\circ$, $\angle adb = 80^\circ$, $\angle c = 25^\circ$. find $m\angle cbd$ in degrees.
$m\angle cbd = \square^\circ$

Explanation:

Step1: Find ∠ADB's supplement

∠ADB is \(80^\circ\), so ∠CDB = \(180^\circ - 80^\circ = 100^\circ\) (linear pair).

Step2: Use triangle angle sum

In △CBD, angles sum to \(180^\circ\). So \(m\angle CBD = 180^\circ - 100^\circ - 25^\circ\)

Step3: Calculate the result

\(180 - 100 - 25 = 55\)

Answer:

55