For the two vectors A and B in Fig. E1.39, find (a) the scalar product A · B

Video transcript

Welcome back everybody. We are asked to find the scalar product of these two given vectors. Well, the scalar product for two vectors is equal to the magnitude of the first vector times the magnitude of the second vector times the cosine of the angle between those two vectors. Now let's go ahead and plug in our vectors here. So we're gonna have that. The scalar product between those two is going to be the magnitude of em given right here, times the magnitude of end given right here times the cosine of the angle between them. Now we don't know that. So we have to calculate that and it is going to be this entire angle right here. That's what we're looking for. So let's calculate that first. We have that data is equal to what we have this part right here, this is going to be 90 - plus this part right here. That's an entire quadrant. So that's just gonna be 90 degrees plus this part right here, which we are given is 28. When you add all this together, you get 100 and 56 degrees, meaning we now have everything to plug into this formula. So let's go ahead and do that. The scalar product between m and n is equal to the magnitude of M, which is 4.2 times the magnitude of n, which is 3.2. And the co sine of the angle between them, which when you plug this into your calculator, you get negative 12. meters squared, which corresponds to our answer choice of the Thank you guys so much for watching Hope. This video helped. We will see you all in the next one.