asked 78.2k views
3 votes
ABCD is a trapezium.

A
D
Calculate the size of the largest angle.
4(2y - 1)
B
30-y
C

asked
User Sequence
by
8.1k points

1 Answer

3 votes

Answer:x = 123.6°

Explanation:

Subdivide the trapezium into a rectangle and triangle.

The triangle is a right triangle with hypotenuse CD and height 12.5cm.

The base of the triangle is 24.3 - 16 = 8.3 cm

To find angle D, use the tan trig ratio:

where is the angle, O is the side opposite the angle A is the side adjacent the angle.

Therefore, for the right triangle:

= D

O = 12.5

A = 8.3

In a quadrilateral, the sum of the angles between the parallel lines is 180°. Therefore, m∠C + m∠D = 180°

⇒ x + 56.41573952... = 180

⇒ x = 180 - 56.41573952...

⇒ x = 123.6° (1 dp)

Alternatively, calculate angle C of the right triangle and add it to 90° to find x.

answered
User Ecjb
by
7.7k points

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