 Hello friends Welcome to this session on lines and angles and we are going to proceed with some more knowledge about different Angle relations. Okay, so here I have mentioned to Really such relations one is called adjacent angles. So we will understand what adjacent angles are and then we'll understand linear pair of angles So here I have drawn a diagram three rays. You can see oh our Oh Q and OP right three rays are there, right now. What are adjacent? Angle guys. So two angles are called adjacent angles. So I'm writing here two angles two angles are called adjacent called Adjacent angles. So you would be Knowing that adjacent means side-by-side. So hence two angles are called adjacent if What are the conditions one? Condition number a they have the same vertex They must have the same Vertex so here in this case you can see Point O is the vertex, isn't it? Then point number B is they have a common arm they have Common arm Common arm in this case. What is a common arm guys? OQ is the common OQ is common to both and point number C is that the Uncommon arms Uncommon arms. So what are uncommon arms in this case? OP and OR should be should be on the opposite side opposite sides of The common arm Okay, so that is how Adjacent angles are described. So hence you can see the angle Another example like that Like that and this so hence here in this case Let's say a o b and C. Okay, so Angle a o b and angle a sorry boc are adjacent Adjacent angles why because they have a common vertex ob is the common arm and o c and o a are on the opposite sides of ob Okay, now what's linear pair of angle guys? So linear pair is nothing but two adjacent angles two adjacent angles are Said to be linear pair when the uncommon arms arms are in opposite direction opposite Direction Okay, so an example is let's say this is one o a Okay, this is exactly opposite direction o b and The common arm is C, right? So hence here angle boc and angle C o a form Linear pair or basically if you notice what what information do we get we get that? you know angle boc and Angle C o a are supplementary This is additional information so in a linear pair In your linear pair the sum of the angles so or you can say angle boc plus angle C o a Is equal to 180 degrees Okay, how we will see in the next session. So please understand we learned two things one is What are adjacent angles and the other thing is linear pair of angles? Okay, so we'll see and Try to prove this particular relation. That is sum of two angles The two angles in the linear pair is always 180 degrees and vice versa. That means if the sum of two Angles in an adjacent angle pair is 180 degree. That means O b is O b and o a are in exact opposite direction. We'll prove this in the next session