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Example 1

Solution

First look at the top triangle (ABC):

BC = 4.377315565 cm = 4.38 cm (two decimal places).

Now look at triangle BCD (working at two decimal places to give an answer to one decimal place):

Example 2

Calculate angle ADB in the following diagram (to one decimal place).

Solution

First look at the lower triangle (BCD):

BC = 15.22229561 cm = 15.22 cm (two decimal places).

Now look at triangle ACD (working at two decimal places to give an answer to one decimal place):

AC = 5.3 + 15.22 = 20.52 cm

Use tan^-1 on calculator to get:

ADC = 54.38°

Now to get angle ADB:

ADB = ADC − BDC

ADB = 54.38° − 46° = 8.38° = 8.4° (one decimal place).