1 00:00:00,600 --> 00:00:07,920 Let's do this question in parliament, Graham, BQ are us all is the midpoint of its Q So that means 2 00:00:07,920 --> 00:00:09,210 it's always equal to all. 3 00:00:09,210 --> 00:00:11,730 Q Now we need to find angle s. 4 00:00:11,730 --> 00:00:13,470 Angle R, side B. 5 00:00:13,470 --> 00:00:14,640 Q You are. 6 00:00:14,670 --> 00:00:17,190 And the diagonal PR was the video. 7 00:00:17,250 --> 00:00:19,580 Give it a try and then let's do it together. 8 00:00:19,950 --> 00:00:20,400 All right. 9 00:00:20,400 --> 00:00:20,880 We are back. 10 00:00:20,880 --> 00:00:23,340 I hope you have given it it right now directly. 11 00:00:23,340 --> 00:00:29,130 We can say that P Q is equal to fifteen centimetre and Q are is equal to eleven centimetre. 12 00:00:29,130 --> 00:00:29,510 Right. 13 00:00:29,520 --> 00:00:34,800 Because P Q Ours is a program and in a programme opposite sides are equal. 14 00:00:34,890 --> 00:00:35,220 Right. 15 00:00:35,460 --> 00:00:36,750 But we have these two things. 16 00:00:36,960 --> 00:00:38,040 Now let's press on. 17 00:00:38,040 --> 00:00:42,900 We need to find angle s and angle are all right now. 18 00:00:42,900 --> 00:00:45,810 Angle B will be equal to sixty degrees. 19 00:00:45,810 --> 00:00:46,140 Right. 20 00:00:46,140 --> 00:00:47,310 Why would that be so. 21 00:00:47,520 --> 00:00:53,580 Because well here Espy's parallel to argue and B why is acting as the transversal. 22 00:00:53,760 --> 00:00:59,550 Therefore this angle over here and this angle over here are corresponding angles and they are equal. 23 00:00:59,550 --> 00:01:02,260 Therefore Angle B is equal to sixty degrees. 24 00:01:02,580 --> 00:01:03,000 All right. 25 00:01:03,180 --> 00:01:08,850 Now in a parallel grand we know that are decent, angles are supplementary or they add up to 180 degrees. 26 00:01:09,000 --> 00:01:12,600 Therefore angle B plus angle S is equal to 180 degrees. 27 00:01:12,780 --> 00:01:16,620 Or I can say that angle s is equal to 180 minus sixty. 28 00:01:16,830 --> 00:01:18,320 That's 120 degrees. 29 00:01:18,660 --> 00:01:19,140 All right. 30 00:01:19,350 --> 00:01:23,280 Now over here you can see angle B and other opposite angles. 31 00:01:23,490 --> 00:01:25,860 And in a program, opposite angles are equal. 32 00:01:26,010 --> 00:01:29,630 Therefore, angle are is equal to angle B that sixty degrees. 33 00:01:29,820 --> 00:01:30,330 All right. 34 00:01:30,570 --> 00:01:34,980 Now we have found angle S and we have found angle on. 35 00:01:35,040 --> 00:01:39,180 So these two parts are also done and we are left with finding diagonal. 36 00:01:39,450 --> 00:01:43,200 We are now we can directly solve it. 37 00:01:43,200 --> 00:01:49,430 If you remember the property that in a program diagonals bisect each other, that would mean be always 38 00:01:49,440 --> 00:01:51,540 equal to or and you will get P. 39 00:01:51,780 --> 00:01:55,290 S six in the two, which is twelve centimetre right now. 40 00:01:55,290 --> 00:01:58,290 You can also think of it in this way triangle or P. 41 00:01:58,290 --> 00:02:03,660 Q is congruent triangle or as so these two triangles are congruent. 42 00:02:03,900 --> 00:02:07,560 Right, because let's mark these angles over here. 43 00:02:07,590 --> 00:02:12,000 You will see that angle one and angle two are equal are vertically opposite angles. 44 00:02:12,120 --> 00:02:14,250 Angle for an angle three are equal. 45 00:02:14,370 --> 00:02:14,760 Why. 46 00:02:14,760 --> 00:02:21,480 Because they are alternating angles because SRN and you are parallel and Eskew is acting as the transposon 47 00:02:21,750 --> 00:02:25,830 and you will see that is always equal to Oakhill because it's given right. 48 00:02:26,070 --> 00:02:31,350 Therefore these two triangles are congruent Asper AC criteria. 49 00:02:31,590 --> 00:02:38,520 Now, because these two are congruent, we can see that B R is equal to people plus or and these two 50 00:02:38,520 --> 00:02:41,760 are equal because these two triangles are fondren. 51 00:02:41,760 --> 00:02:42,150 Right. 52 00:02:42,240 --> 00:02:45,510 So that gives you six plus six, which is equal to twelve centimetre. 53 00:02:45,660 --> 00:02:51,180 Now you don't need to do this in the exam because you know that in a program diagonals bisect each other. 54 00:02:51,300 --> 00:02:53,820 So if this is six centimetre definitely. 55 00:02:53,820 --> 00:02:57,060 Or are is also six centimetre and equal and you can directly. 56 00:02:57,060 --> 00:02:57,330 Right. 57 00:02:57,330 --> 00:03:00,300 That bar is equal to twelve centimetre.