Right Triangle Angle Calculation: Finding ∠CBD with Given 30° Angle

Question

ABC Right triangle

If $∢\text{BAC}=30$

Calculate the size of $∢\text{CBD}$

Note that angle BDA equals 90 degrees, therefore we can deduce that angle BDC also equals 90 degrees.

Let's look at triangle ABC and calculate angle C, since angles A and B are given to us:

$180-90-30=60$

Now let's focus on triangle BDC and calculate angle alpha, since we have calculated the other two angles.

$180-90-60=30$