Ex 11.1, 4
Construct the following angles and verify by measuring them by a Protractor :
75°
75° = 60° + 15°
75° = 60° + (𝟑𝟎°)/𝟐
So, to we make 75° , we make 60° and then bisector of 30°
Steps of construction
Draw a ray OA.
Taking O as center and any radius, draw an arc cutting OA at B.
3. Now, with B as center and same radius as before,
draw an arc intersecting the previously drawn arc at point C.
4. Now, with C as center, and same radius,
draw another arc intersecting the previously drawn arc at point D
5. Draw ray OE passing through C
and ray OF passing through D
Thus, ∠ AOE = 60°
and ∠ EOF = 60°
6. Taking C and D as center , with radius more than 1/2CD,
draw arcs intersecting at P.
7. Join OP
Thus, ∠ AOE = 60°
and ∠ EOF = 60°
6. Taking C and D as center , with radius more than 1/2CD,
draw arcs intersecting at P.
7. Join OP
Thus, ∠ EOP = 30°
Now, we bisect ∠ EOP i.e. (30°)/2 = 15°
7. Mark point Q where OP intersects the arc
8. Taking Q and C as center , with radius more than 1/2QC,
draw arcs intersecting at R.
9. Join OR
Thus, ∠ AOR = 75°
On measuring the ∠ AOR by protractor, we find that ∠ AOR = 75°
Thus, the construction is verified

Made by

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths and Science at Teachoo.