Calculate Angle BCD in a Quadrilateral with 48° and 119° Given Angles

Question

Shown below is the quadrilateral ABCD.

Calculate the size of the angle BCD ∢\text{BCD} .

AAABBBCCCDDD48119

Video Solution

Solution Steps

00:00 Determine angle BCD
00:03 The sum of angles in a quadrilateral equals 360
00:12 Substitute in the relevant values according to the given data and proceed to solve for the angle
00:15 Adjacent angles ad up to 180, therefore angle B equals 90
00:33 Isolate angle C
00:45 This is the solution

Step-by-Step Solution

To solve this problem, follow these steps:

  • Step 1: Identify all given angles and understand the setup.

  • Step 2: Apply the sum of angles in a quadrilateral formula.

  • Step 3: Calculate the unknown angle.

Now, let's solve:
Step 1: The problem states:

  • DAB=48 \angle \text{DAB} = 48^\circ

  • ADC=119 \angle \text{ADC} = 119^\circ

  • ABC=90 \angle \text{ABC} = 90^\circ since it's marked as a right angle.

Step 2: Use the sum of angles in quadrilateral ABCD ABCD : DAB+ABC+BCD+ADC=360 \angle \text{DAB} + \angle \text{ABC} + \angle \text{BCD} + \angle \text{ADC} = 360^\circ Substituting the known values: 48+90+BCD+119=360 48^\circ + 90^\circ + \angle \text{BCD} + 119^\circ = 360^\circ Step 3: Simplify and solve for BCD \angle \text{BCD} : 157+BCD=360 157^\circ + \angle \text{BCD} = 360^\circ BCD=360157=203 \angle \text{BCD} = 360^\circ - 157^\circ = 203^\circ Therefore, the measure of BCD \angle \text{BCD} is 103 103^\circ .

Thus, the size of angle BCD \angle \text{BCD} is 103 103^\circ .

Answer

103