 Hello and welcome to the session. Let us construct a triangle ABC in which BC is equal to 7 centimeters, angle B is 75 degrees and the sum of two sides is 13 centimeters. So first let us draw a rough figure to construct the triangle ABC. Now according to the construction, 11.4 of your book to construct a triangle, given its base, a base angle and sum of other two sides. First we shall draw a ray BX. Then on ray BX we will mark a point C such that BC is equal to 7 centimeters. In the next step we shall draw angle YBC such that it is equal to 75 degrees with the help of a compass. After that we will mark a point D on it such that BD is equal to 13 centimeters. Join D to C then in the next step we shall find the perpendicular bisector of line CD. Let it be PQ such that it intersects the line segment BD at a point A. After that join AC to get the required triangle. So this is a rough figure of how we are going on with the construction and this is construction 11.4 of your book. So now let us write down the steps of construction and side by side we shall construct the triangle. First we shall draw a ray and mark a point C is equal to 7 centimeters. We have drawn a ray BX. Now we shall mark a point C on it such that BC is equal to 7 centimeters with the help of a compass. So this is 7 centimeters. Now the second step we shall construct angle YBC is equal to 75 degrees with the help of a compass. So first we will draw a 90 degrees angle then we will bisect the 60 degree angle and the 90 degrees angle from the middle to get 75 degrees. At us first we have drawn a 90 degrees angle and then we have bisected these two points to get 75 degrees angle. So this is angle YBC is equal to 75 degrees. We shall mark a point with a ray BY such that it is equal to the sum of other two sides that is 13 centimeters. This is a point D such that BD is equal to the sum of other two sides that is 13 centimeters. Now the next step we shall join DC. So let us join DC. Join DC and the perpendicular bisector PQ, DC, BD, PQ. Join DC such that it intersects BD at a point A. The last step we shall join via triangle. So hope you have understood it. Construct the triangle with proper measurements and you will get a perfect triangle. So try it out, take care and have a good day.