Lines $WX$ and $YZ$ are parallel. One angle is $77°$. Find $a,b$ and $c$.

$AB$ and $CD$ are parallel lines. Calculate $s$ and $t$.

Look at the diagram. Explain why these two lines cannot be parallel.

This shape is made from eight identical triangles. Sketch the diagram and label the other angles equal to $a, b$ or $c$.

This shape is made from eight identical triangles. Use this fact to calculate the missing angles.

The diagram shows angle $X$ is $45°$. Calculate $a$.

The diagram shows angle $X$ is $45°$. Angle $X$ is increased to $90°$. Find the new value of $a$.

The diagram shows angle $X$ is $45°$. Angle $X$ is increased to $119°$. Find the new value of $a$.

The diagram shows angle $X$ is $45°$. Can angle $X$ be more than $119°$? Give a reason for your answer.