Please help me with this problem Calculate the Area of the T

Calculate the Area of the Triangle below A plane was observed in the sky by Jones and Trooper on the ground from different positions. Jones is 7km away from trooper. Jones observes the plane at 35 degree and the straight distance from Jones to the Plane is 155 km. Interpret and sketch with straight lines the position of the plane in relation to the position of Jones and Trooper. Calculate the Area of the figure you sketched in (a) above.

Solution

Area of triangle= (a*b/2) sin C

a and b are corresponding sides and C is the including angle

In this question a=13,b=8 and C=85

Therefore

Area=(13*8/2)sin 85 = 52 sin 85=51.8