Parts of a Triangle: Using angles in a triangle

AB || CD

x = 80

Calculate the size of the $\alpha$.

30

AB||CD

x = 50

Calculate the size of angle $\alpha$.

67

Look at the triangle below.

Calculate the size of angle $\alpha$.

103

AB || CD

Calculate the size of the angle $\alpha$.

43

AB || CD

Calculate the size of angle $\alpha$.

84

ABC is an obtuse triangle.

$∢C=\frac{1}{2}∢A$$$

$∢B=3∢A$

Is it possible to calculate $∢A$?

If so, then what is it?

Yes, 40°.

ABC is a right triangle.

$∢A=20°$

Is it possible to calculate the size of $∢C$?

If so, what is it?

Yes, 70°.

Given the triangle ABC.

Dado ∢B>90° , $∢A=20°$

Is it possible to calculate a ? $∢B$?

If so, find how much the angle is equal to.

$$

No

Shown below is the triangle ABC.

$∢A$ is 3 times greater than the sum of the rest of the angles.

Calculate $∢A$.

135°

The triangle ABC is isosceles.

$∢C=50°$

Is it possible to calculate the size of angle $∢A$?

If so, then what is it?

Yes, 80°

The triangle ABC is right angled.

$∢A=4∢B$

Calculate angles $∢B$ and $∢A$.

72 , 18

ABC is an isosceles triangle.

DE is parallel to BC.

Angle A is equal to 3X plus 22.

Express the size of angle DEC.

$101+1.5x$