1. **State the problem:**
We have trapezoid ABCD with legs BC and AD, DE perpendicular to CB, and given angles $m\angle A = 86^\circ$ and $m\angle C = 74^\circ$. We want to find the measures of $m\angle B$ and $m\angle ADE$.
2. **Recall trapezoid angle properties:**
In trapezoid ABCD, the sum of the interior angles is $360^\circ$.
Also, consecutive angles between parallel sides are supplementary.
3. **Find $m\angle B$:**
Since ABCD is a trapezoid, angles $A$ and $B$ are consecutive angles on the same leg AD.
We use the fact that $m\angle A + m\angle B = 180^\circ$ (because AD is a leg and AB is parallel to DC).
Calculate:
$$m\angle B = 180^\circ - m\angle A = 180^\circ - 86^\circ = 94^\circ$$
4. **Find $m\angle D$:**
Similarly, angles $C$ and $D$ are consecutive angles on leg BC.
They satisfy:
$$m\angle C + m\angle D = 180^\circ$$
Calculate:
$$m\angle D = 180^\circ - 74^\circ = 106^\circ$$
5. **Find $m\angle ADE$:**
Since $DE \perp CB$, $m\angle DEB = 90^\circ$.
Point E lies on segment CB, so triangle ADE is formed with $DE \perp CB$.
In triangle ADE, angles sum to $180^\circ$:
$$m\angle ADE + m\angle DEA + m\angle EAD = 180^\circ$$
We know $m\angle DEA = 90^\circ$ (right angle at E).
Angle $m\angle EAD$ is part of $m\angle A$, so:
$$m\angle EAD = m\angle A = 86^\circ$$
Calculate $m\angle ADE$:
$$m\angle ADE = 180^\circ - 90^\circ - 86^\circ = 4^\circ$$
**Final answers:**
$$m\angle B = 94^\circ$$
$$m\angle ADE = 4^\circ$$
Trapezoid Angles 3B03Fc
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