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7cm
8
6cm
8am
U
ABD is a triangle in which AB = 7 cm and The point E on AD and the point C on BD are such that BE = 6 cm, BC = 8cm ane
ZCBE = 20°
Calculate to 3 significant figures,
(a) the length, in cm, of CE,
(b) the size, in degrees, of ZBCE,
(c) the length, in cm, of ED,
(d) the size, in degrees, of ZABE,
(e) the area, in cm², of AABD.

1 Answer

3 votes

Final answer:

To solve this problem, use the properties of triangles and angles. Find CE using the Law of Sines and find angle ZBCE using angle sum in a triangle. Also find ED using angle sum in a triangle. Finally, find ZABE using the Law of Sines and find the area of triangle ABD using the formula for the area of a triangle.


Step-by-step explanation:

To solve this problem, we will use the properties of triangles and angles. Let's start by finding CE:

In triangle BDE, we have angle BDE + angle EBD + angle BED = 180°.

Since we know that angle BDA = 25°, we can calculate angle BDE as 180° - 25° - 20° = 135°.

In triangle CBE, we can use the Law of Sines to find CE:

sin(135°)/6 = sin(20°)/CE.

Solving for CE, we find CE ≈ 5.78 cm.

Now, let's find angle ZBCE:

Using the fact that the sum of the angles in a triangle is 180°, we have:

angle ZBCE = 180° - 20° - 45° = 115°.

For part (c), we can use the fact that the sum of the angles in a triangle is 180° to find angle BDE:

angle BDE = 180° - 135° - 20° = 25°.

Finally, for part (d), we can use the Law of Sines in triangle ABE to find angle ZABE:

sin(25°)/7 = sin(ZABE)/6.

Solving for ZABE, we find ZABE ≈ 55.3°.

To find the area of triangle ABD, we can use the formula:

Area = (1/2) * AB * BD * sin(BDA).

Plugging in the values, we get:

Area = (1/2) * 7 * 8 * sin(25°) ≈ 18.0 cm².


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