If find the value of .

If two complimentary angles are in the ratio of 4:5, find the greater angle.

Given that (a²+b²)=60, then find the value of (a+b)²+(a–b)².

Triangle PQR is such that PQ=9 cm, QR=6 cm, PR=7.5 cm and triangle PQR is similar to triangle XYZ. If XY=18 cm, find the value of YZ.

If the angles of a triangle are in the ratio of 1:4:7, then find the ratio of the greatest angle to the smallest angle.

Each exterior angle of a regular polygon measures 9°. How many sides does the polygon have?

If the following figure, AC||BD, ∠CAF = 25^o, ∠DBG = 65^o and BF = BA, then ∠BFE is equal to -

In triangle ABC a straight line parallel to BC intersects AB and AC at D and E respectively. If AB = 2AD then DE : BC is